Obviously it's the right one.

Just look at that ancient computer tower. The left one is older.

These pics were taken just a month apart in 2011, but deadmau5 went cheese before Galaga, so the right one is older.

You should feel pretty embarrassed if you got this one wrong.

Lack of arm tattoos is the tip-off. The one on the right is old school deadmau5.

Mickey Mouse was around decades before deadmau5 was even a glimmer in Joel Zimmerman's eye. The Disney mascot is 86 years old, while Zimmerman is a sprightly 33.