They are heroes in a half-shell... and all the letters of the alphabet.

More details at http://baboondesign.blogspot.com/2011...-abcs.html.

Depicted are: Ace Duck, Bebop, Chrome Dome, Donatello, Doctor El, Foot Soldier, General Traag, Hothead, Irma, Casey Jones, Krang, Leonardo, Michaelangelo, Napoleon Bonafrog, April O'Neil, Pizzaface, Dr. Quease, Raphael, Shredder, Triceraton, Utrom, Vernon, Wingnut, Dr. X, Usagi Yojimbo, Zak