The Skull Cannon is a recurring enemy in the Rosenkreustilette series.
Taking the form of giant skulls the size of the human characters, they open their mouths to fire at the player. The standard Skull Cannons open their mouths to launch cannonballs at the player when she comes near. They are based on the Cannon enemies in Mega Man 3.
In Rosenkreuzstilette, they appear in the Imperial Training Hall (the opening stage), Luftfeste Sleipnir (Luste's stage), the Ghost Town (Grolla's stage), The Fortress City of Zuverburg (Sichte's stage), stages 2, 3 and 4 of Zeppelin's Castle, and stage 2 of Iris Palace. In Rosenkreuzstilette Freudenstachel, they appear in the Castle Grounds (the opening stage), Ghost Town/Mountainside Dungeon (Grolla's stage) , and the Zuverburg Clock Tower (Sichte's stage).
The Skull Flamer is a tan Skull Cannon that shoots a stream of fire out of its mouths instead of cannon balls. They are based on the Flamer enemies in Mega Man X.
In Rosenkreuzstilette. they appear in Luftfeste Sleipnir and stage 3 of Zeppelin's Castle. In Rosenkreuzstilette Freudenstachel, they appear in the Castle Grounds, the version of Ghost Town that appears in early versions of the trial, and the Zuverburg Clock Tower.