Jesper Kyd wrote the main theme for the original Assassin's Creed video game.
Kyd composed the soundtrack for the first Assassin's Creed, released in 2007. The score combines orchestral writing with choral and electronic textures, helping establish the series' distinctive atmosphere of historical drama, stealth, and mystery. Its music accompanies Altaïr's missions in the Crusades-era Holy Land.
Kyd later composed music for Assassin's Creed II, Brotherhood, and Revelations, making him one of the franchise's most important recurring composers. His work on Ezio's games is often remembered alongside the original score when fans discuss the series' musical identity.
Lorne Balfe composed Assassin's Creed III and contributed to other franchise music. Sarah Schachner worked on Origins and Valhalla, while Austin Wintory composed Assassin's Creed Syndicate's companion score. Those composers are connected to the series but not the original game's main theme.