1673: Molière, the French actor and playwright, who suffered from pulmonary tuberculosis, died after being seized by a violent coughing fit while playing the title role in his play Le Malade imaginaire (The Hypochondriac). The superstition that green brings bad luck to actors is said to originate from the colour of the clothing he was wearing at the time of his death.
1817: An actor known as Mr. Cummins died on stage while playing the part of Dumont in The Tragedy of Jane Shore by Nicholas Rowe, at the Leeds Theatre in Hunslet. He died of 'ossification of the heart' (aortic stenosis) on 20 June having uttered his final words from the play "May such befall me at my latest hour ...".
1820: Madame Delinsky, the female half of a magic act, was accidentally shot and killed while performing the "bullet catch" trick. One of the six gunmen mistakenly loaded his rifle with a live bullet.
1840: Magician Arnold Buck was killed while performing the "bullet catch" trick. The volunteer from the audience was given the gun and a bullet to load onstage; the bullet was a blank, but unbeknownst to Buck, the audience member inserted some nails into the gun barrel.
1872: Lion tamer Thomas Macarte, known as Massarti the Lion Tamer, who had previously lost an arm when attacked by one of the lions, entered the lion's cage for a performance with a travelling menagerie in Bolton market on 3 January. Attacked by the lions, he attempted to fight them off with his sword and a pistol loaded with blanks but they overcame him. Although other members of the show eventually forced the animals back into an inner cage they dragged Macarte with them. Eventually rescued, he died on the way to the hospital. 
1873: The actress Matilda Pascaly died from injuries suffered on stage while playing the part of an angel in Don Juan de Maraña. Stagehands mishandled her wires and sent her crashing upside down into a wall.
1882: The actress Annie Von Behren died during a performance of Si Slocum at Cincinnati‘s Coliseum when a firearm wielded by her co-actor, Frank Frayne, accidentally discharged, shooting her in the head.
1904: Emil Hasda, a Polish comic actor, took six curtain calls after a performance in Nimptsch, Poland (at the time part of Germany) on 11 April before shooting himself in the head in front of the audience, apparently because a female member of the company had rejected his marriage proposal. 
1911: Sigmund Neuberger, a vaudeville performer known as "The Great Lafayette," died on 9 May in Edinburgh's Empire Palace Theatre while performing his "Lion's Bride" illusion after a stage lamp sparked a fire that killed Neuberger, his double, the lion, and ten other performers.
1927: John "Chuck" O'Connor, performer in vaudeville and father of actor Donald O'Connor, died of a heart attack while dancing onstage in their family act.
Escape artist Genesta drowned during his milk-can escape, a stunt associated with Harry Houdini. Unbeknownst to Genesta, his milk can had been dropped, damaging the secret escape hatch and rendering it inoperable. His assistants were unaware of this, and freed him too late.
Alexander Woollcott suffered a heart attack during a Writers' War Board panel on CBS Radio in which he and four other individuals were having a discussion about Hitler. Listeners were oblivious to the fact that anything was out of the ordinary. Several of them reported that Woollcott, known for being strongly opinionated, was unusually quiet.
Gareth Jones was portraying a character who died of a heart attack in a live science fiction play Underground in ABC Television's Armchair Theatre television series (30 November) when he died of a real heart attack between his scenes. The actors and director improvised to account for his absence.
Tyrone Power was stricken by a massive heart attack while filming a dueling scene with his frequent co-star and friend, George Sanders for the film Solomon and Sheba. He died while being transported to the hospital in Madrid on 15 November, aged 44.
Singer Leonard Warren expired after performing his aria in the second act of the opera La forza del destino at the New York Metropolitan Opera. He was then to perform Don Carlo's act III aria, which begins Morir, tremenda cosa ("to die, a momentous thing"), when he started coughing and gasping. He fell face first to the ground, and it was revealed he had died of a massive heart attack.
1967: Comedian and singer Jodie "Butterbeans" Edwards, the surviving member of the long-running vaudeville duo Butterbeans and Susie, died on 28 October as he walked onstage at the Dorchester Inn, outside Chicago.
1968: Joseph Keilberth, conductor, died in Munich after collapsing while conducting Wagner's Tristan und Isolde in exactly the same place as Felix Mottl had done in 1911.
Professional wrestler Mike DiBiase suffered a heart attack in the ring while wrestling his opponent Man Mountain Mike on 2 July in Lubbock, Texas. CPR was unsuccessful, and an autopsy revealed coronary artery disease. DiBiase was the father of wrestling star Ted DiBiase.
Country music star Spade Cooley died from a heart attack while backstage during the intermission of a benefit concert in Oakland, California on 23 November. Cooley was serving a life term in prison for beating his wife to death in front of their daughter, and played the show on a weekend furlough. He was scheduled to be paroled three months later, in February 1970.
Longevity expert Jerome Rodale was a guest on The Dick Cavett Show. After his interview was done, Pete Hamill was being interviewed by Cavett when Rodale slumped. Hamill, noticing something was wrong, said in a low voice to Cavett, "This looks bad." Rodale had died of a heart attack at age 72. The episode was never aired.
Luther Lindsay, one of the first black stars in professional wrestling, died of a heart attack at the end of a match. Lindsay had just delivered his winning move, and died while lying on top of his opponent.
10 September: Finnish magician Aimo Leikas [fi] killed himself in front of a crowd while performing his Russian roulette act. He had been performing the act for about a year, selecting six bullets from a box of assorted live and dummy ammunition.
Jayan, the biggest star in Malayalam cinema, was killed in a helicopter accident while re-filming a stunt for the action movie Kolilakkam. Jayan was hanging onto the helicopter's landing skids when it crashed, and later succumbed to his injuries.
Danish actor and comedian Dirch Passer suffered a fatal heart attack backstage immediately prior to going on stage in Tivoli Gardens on 3 September 1980.
Vic Morrow and two children, My-Ca Dinh Le (age 7), and Renee Shin-Yi Chen (age 6), died in an accident while filming on location for the Twilight Zone: The Movie in Ventura County, California. Morrow, Le, and Chen were filming a scene set during the Vietnam War in which their characters attempt to escape from a pursuing U.S. Army helicopter out of a deserted Vietnamese village. The helicopter was hovering at about 25 feet above them when pyrotechnic explosions damaged it and caused it to crash on top of them, killing all three instantly.
Actor and comedian Joe E. Ross suffered a heart attack and died while performing on stage on the evening of 13 August. His wife reportedly collected just half of Ross's fee because he had failed to do a full show.
Actor Jon-Erik Hexum died after shooting himself with a blank pistol. On 12 October 1984, the cast and crew of the TV series Cover Up were filming the seventh episode of the series, "Golden Opportunity", on Stage 17 of the 20th Century Fox lot. One of the scenes filmed that day called for Hexum's character to load blanks into a .44 Magnum handgun. When the scene did not play as the director wanted, there was a delay in filming. Hexum became restless during the delay and began playing around to lighten the mood. He had apparently unloaded all but one blank round when, at 5:15 p.m., he spun the cylinder and, as if playing Russian roulette, put the revolver to his right temple and pulled the trigger. The force of the blank round was sufficient to dislodge fragments of his skull, which acted as projectiles in lieu of a bullet loaded in the cartridge. The skull fragments were propelled into his brain, killing him instantly.
Magician and comedian Tommy Cooper suffered a heart attack during a performance on the London Weekend Television variety show Live From Her Majesty's. Cooper was known for getting his illusions deliberately and comically wrong. After Cooper collapsed, his audience laughed for almost a minute, thinking that his stage character had swooned at the appearance of a pretty magician's assistant (even she thought Cooper was improvising a comic bit). The TV show cut away to an unscheduled break. Efforts to revive Cooper backstage failed, and he was taken to a hospital where he was pronounced dead on arrival.
Butoh dancer Yoshiyuki Takada was performing The Dance of Birth and Death with a Tokyo artistic troupe, on the side of Seattle's Mutual Life building. His rope broke, and he fell six stories to his death.
Stunt performer Dar Robinson died in a motorcycle accident while on the set of Million Dollar Mystery as he attempted a stunt, but ended up accidentally riding off a cliff to his death.
Actress Edith Webster died onstage from a heart attack while performing her death scene in the play "The Drunkard," in a lodge in Baltimore. The role called for her to sing "Please Don't Talk About Me When I'm Gone," and then slump to the floor, which she did.
Saxophonist Warne Marsh collapsed at a Los Angeles jazz club while soloing on the standard "Out of Nowhere".
Comedian Dick Shawn died on stage while performing at the University of California, San Diego after suffering a fatal heart attack. He lay motionless on the stage for several minutes, while audience members (thinking it was part of his act) began shouting comments, such as: "Take his wallet" and "How long is this going to go on?". The stage manager came out to check on Shawn several times before realizing it was not part of the show. A doctor was called up from the audience to perform CPR on the comedian until the paramedics arrived. He was later pronounced dead at Scripps Memorial Hospital.
1990: Escape artist Joseph "Amazing Joe" Burrus died on Halloween when the glass 'coffin' he was attempting to escape from collapsed under the weight of wet cement poured on top of it.
1991: Actor Redd Foxx suffered a fatal heart attack on the set of the CBS sitcom The Royal Family. It was noted that initially cast mates on set thought Foxx was only fooling around after he clutched a chair and fell to the floor, since his character on Sanford and Son often faked heart attacks.
22 February, Polish actor Tadeusz Łomnicki died of a heart attack during one of the last dress rehearsals of Shakespeare's King Lear, in which he was playing the lead role, much awaited by public and critics. The piece was due to be premiered a week later.
On 3 May, Indian film actor Alummoodan died of a heart attack while performing at the sets of Adwaitham. He died on the arms of co-star Mohanlal while filming.
Brandon Lee, son of martial artist Bruce Lee, died while filming the movie The Crow in Wilmington, North Carolina. A prop gun had been squib loaded, causing the blank cartridge to propel the bullet into Lee and kill him. Contrary to urban legend, the footage of his death was not kept in the movie. Instead, they re-shot the scene using a different actor, whose death in the film was by a throwing knife.
On 11th June 1993, English comic actor Bernard Bresslaw died of a sudden heart attack in his dressing room at the Open Air Theatre in Regent's Park, London, where he was to play Grumio in the New Shakespeare Company's production of Taming of the Shrew.
Singer Tiny Tim suffered a fatal heart attack while turning to leave the stage during a benefit concert in Minneapolis.
Motocycle daredevil Butch Laswell died in Mesquite, Nevada, attempting to set a new world record by jumping over a 38-foot-high (12 m) pedestrian bridge. While in the air, Laswell was blown off course by crosswinds; pushing him to the left of the landing ramp. He flatlanded and crashed.
Turkish singer Zeki Müren died of a heart attack during a live performance on stage.
Opera singer Richard Versalle died on stage at the Metropolitan Opera during the company's première performance of The Makropulos Case when he suffered a heart attack while standing on a sliding ladder attached to a file cabinet. He was stricken after singing the line, "Too bad you can live only so long."
Dutchman Coen van Vrijberghe de Coningh died of cardiac arrest during a performance of the television series Flodder. He and another actor drove in a Chevrolet. While jumping onto the hood, he fell and died. The audience thought it was part of the show, but the actors were aware of what had happened.
Paolo "Feiez" Panigada, member of the Italian band Elio e le Storie Tese, died of a brain haemorrhage while performing onstage.
Owen Hart, a Canadian-born professional wrestler for WWF, died during Over the Edge, a pay-per-view event, when performing a stunt. It was planned to have Hart come down from the rafters of the Kemper Arena on a safety harness tied to a rope to make his ring entrance. The safety latch was released and Hart dropped 78 feet (24 m), bouncing chest-first off the top rope resulting in a severed aorta, which caused his lungs to fill with blood.
Mark Sandman, bassist and lead vocalist for the band Morphine, collapsed on stage at the Giardini del Principe in Palestrina, Latium, Italy (near Rome) while performing with Morphine. He was pronounced dead of a heart attack.
Saudi Arabian singer Talal Maddah collapsed and died suddenly on Al Meftaha Stage (Arabic: مسرح المفتاحة) in front of his fans just after performing the intro to one of his popular oldie songs. The concert was aired live on Saudi national television.
2005: 3 October: Franco Scoglio, Italian football manager and sport TV commenter, died of a heart attack while on the air during a program on the Genoan private TV station Primocanale, after a heated discussion over the phone with Genoa chairman Enrico Preziosi. He passed out in his seat while Preziosi continued with his call.
2011: 3 March: Swedish comedian Lasse Eriksson died during the final number of his show Fyra lyckliga män 2(Four happy men 2) at Reginateatern in Uppsala, Sweden. He was one of Sweden's first stand-up comedians.
21 March: Mexican wrestler Perro Aguayo Jr. suffered fatal cardiac arrest caused by cervical spine damage during a match. The severity of Aguayo's condition was not immediately apparent because he fell awkwardly and was draped limply onto the ring ropes, a position that is typically assumed by opponents of Rey Mysterio, another wrestler in the match.
30 October: Four of the five members of the Romanian metalcore band Goodbye to Gravity died during the Colectiv nightclub fire. The band's pyrotechnics, consisting of sparkler firework candles, ignited the club's flammable polyurethane acoustic foam, and the fire spread rapidly, killing 62 people in total. Guitarists Mihai Alexandru and Vlad Țelea were pronounced dead on the scene, while drummer Bogdan Enache and bassist Alex Pascu died shortly thereafter in the hospital due to injuries sustained in the fire.
3 April: Indonesian dangdut singer Irma Bule died during a performance in Karawang, West Java after she was bitten by a king cobra she brought on stage as a prop. She continued singing for 45 minutes after being bitten before she collapsed and died. 
8 October: Taiwanese singer Kuo Chin-fa collapsed on stage during a performance in Kaohsiung. He was then declared dead in a hospital of cardiorespiratory failure.
3 January: Nepali actor Bishnu Bhakta Phuyal died while acting on stage. He fainted during a performance at the theater in Kathmandu.
18 March: Original Boston drummer Sib Hashian died after collapsing during a performance on the Legends of Rock cruise.
1 May: Guitarist and jam band performer Colonel Bruce Hampton collapsed and died of a heart attack during a jam at an all-star concert held in honor of his 70th birthday at the Fox Theatre in Atlanta, Georgia. Hampton collapsed in the middle of a performance of "Turn On Your Love Light", while guitarist Brandon Niederauer took a solo, an action that the other musicians on stage first assumed was humorous act of homage by the quirky, older musician to the younger guitarist before they realized Hampton was not moving. Before his death, Hampton had often joked to friends and journalists that he would prefer to die onstage if given the choice.
19 July: French barefoot singer Barbara Weldens collapsed while performing in a church in Gourdon, France, apparently from electrocution from a faulty cable on the floor.
17 September: Laudir de Oliveira, Brazilian percussionist and former member of the band Chicago, died of a heart attack during a performance in Rio de Janeiro, Brazil.
11 April: Comedian Ian Cognito died of a heart attack during a show in Bicester. He is reported to have "sat on a chair and laid back for five minutes," with audience members initially believing it to be part of his routine until the event's compère called an ambulance.
18 January: Singer-songwriter David Olney died in Santa Rosa Beach, Florida while at the 30A Songwriters Festival. While performing alongside Amy Rigby, he became motionless. Fellow performer Scott Miller said, "David was playing a song when he paused, said 'I'm sorry' and put his chin to his chest. He never dropped his guitar or fell off his stool. It was as easy and gentle as he was."
^Shawn G. Kennedy (October 7, 1984). "Leonard Rossiter, Actor Dies". New York Times. Retrieved 2015-09-13. Leonard Rossiter, one of Britain's most popular comic actors, collapsed during a performance in London and died Friday night, apparently of a heart attack. Mr. Rossiter, who was 57 years old, was declared dead at Middlesex Hospital. ...