Jeffy

Jeffy is an evil destructive dictator puppet from SML Videos as well as the imaginary dropped-off son of Mario.

Despite Mario's beliefs, Jeffy does not exist and is really just Mario's inner demon. Rosalina continuously scolds him for this.

All of Mario's failure adventures with Jeffy are hallucinations.

He thinks Mario and Rosalina are his parents when in reality, they are his guardians.