Lassila is a Finnish surname. Notable people with the surname include:
Carolus Lassila, Finnish diplomat Kalle Lassila, Finnish cross country skier Lydia Lassila, Australian freestyle skier Ora Lassila, Finnish computer scientist Teemu Lassila, Finnish ice hockey player Väinö Lassila, Finnish physician, anatomist, anthropologist and human rights activist Algot Untola (pen name Maiju Lassila), Finnish writer and journalist