S
- Sadako Yamamura (The Ring)
- Sardius (Super Ghouls'n Ghosts)
- Sargatanas (God's Demon)
- Satan (Umineko no Naku Koro Ni)
- Satan (Blue Exorcist)
- Sauron (J. R. R. Tolkien's Middle-earth books), a.k.a. the Dark Lord, the Necromancer, the Eye, the Lord of the Rings
- Sammael, the Desolate One, aka Lord of Resurrection (Hellboy)
- Savanti Romero (Teenage Mutant Ninja Turtles)
- Scanty (Panty & Stocking with Garterbelt)
- Scarlet Van Halisha (Lineage II)
- Scarmiglione (Dante's Inferno)
- Scorpion (Mortal Kombat)
- Screwtape (C.S. Lewis, The Screwtape Letters)
- Scumspawn (Andy Hamilton, Old Harry's Game BBC radio comedy)
- Sebastian Michaelis (Kuroshitsuji)
- Seloth (G.P. Taylor, Shadowmancer)
- Serguthy (Egyptian History hieroglyphics)
- Sepulchure (DragonFable and AdventureQuest Worlds online role-playing games)
- Shang Tsung (Mortal Kombat)
- Shao Kahn (Mortal Kombat)
- Shax (Charmed TV series)
- Shendu (Jackie Chan Adventures TV series)
- Silitha (Darksiders)
- Simon Cartwright (The Ugly)
- Slaanesh (Warhammer Fantasy)
- Slender Man (Slender: The Eight Pages Video game, Creepypasta character)
- The Source of All Evil (Charmed TV series)
- Solomon Grundy (Batman Arkham City)
- Sparda (Hideki Kamiya, Devil May Cry video game series)
- Spawn (Image Comics)
- Spine (The Demonata)
- Straga (Darksiders)
- Sweeney Todd (Sweeney Todd: The Demon Barber of Fleet Street)
- The Stygian (Darksiders)
Read more about this topic: List Of Fictional Demons