Shinichi Sekizawa (関沢新一 Sekizawa Shin'ichi) (June 2, 1921 in Kyoto, Japan – November 19, 1992) was a Japanese screenwriter. His very first screenplay was for the independently-produced film (though distributed by Shintoho Studios) Fearful Attack of the Flying Saucers, which was also his sole directing credit. He went on to script several films by Ishirō Honda, including several classic Godzilla films. He also contributed material to the original Ultraman series and several Tōei Dōga films such as Jack and the Witch.
His scripts for kaiju films have been noted for their inventiveness and for having a more lightweight, "fun" tone than those written by Takeshi Kimura (aka Kaoru Mabuchi), another leading writer of kaiju films, whose scripts had a darker, more serious sensibility.