Super Mario Galaxy
They first appear in this game, where they first appear in Flipswitch Galaxy, where one is found near a Power Star. They also appear in Battlerock Galaxy and Dreadnought Galaxy. Sentry Beams are always found attacking in one spot, and if Mario touches their laser, he will get damaged. Mario must jump twice to expose the spring on the top of its head.
Super Mario Galaxy 2
Only one appears in this game, in Space Storm Galaxy.
- Super Mario Encyclopedia