Evil Leonardo is one of the Evil Turtles in the Turtles of Terror issue of the Fleetway comics. He lives on an alternate Earth where its counterpart of the Hero Turtles are criminals. He is the inventor of the group.
Shredder brings the Evil Turtles from their dimension to the Technodrome to defeat the good Turtles. He will not send them back to their own dimension until they complete this task. When the Evil Turtles kidnap the good Leonardo, Evil Leonardo takes his place in Turtle Lair. After the Evil Turtles are eventually defeated, Evil Leonardo and his brothers are teleported away by Shredder.