Sep is a masculine given name and nickname, often a short form of Septimus. It may refer to:

  • Sepandar Kamvar (born 1977), American computer scientist, artist, author and entrepreneur
  • Sep Lambert (1876–1959), Irish cricketer
  • Sep Ledger (1889–1917), South African rugby union player
  • Sep Ruf (1908–1982), German architect and designer
  • Sep E. Scott (1879–1965), British painter, illustrator and comics artist
  • Sep Smith (1912–2006), English footballer
  • Sep Vanmarcke (born 1988), Belgian road racing cyclist
  • Sep Visser (born 1990), Dutch international rugby union player