Tassilo may refer to:
- Tassilo I of Bavaria (died c. 610)
- Tassilo II of Bavaria (died c. 719)
- Tassilo III of Bavaria (died c. 796)
- Tassilone (1709), an opera by Agostino Steffani (1653–1728)
- Tassilo von Heydebrand und der Lasa (1818–1899), German chess-master
- Prince Tassilo Festetics von Tolna (1850 - 1933), Hungarian nobleman
- Tassilo Thierbach (born 1957), German figure-skater
- Prince Tassilo of Bulgaria (born 2002), grandson of former Tsar Simeon II of Bulgaria