Teenage Mutant Ninja Turtles #21

The longest running TMNT series continues as new dangers and enemies force the Turtles to make tough choices! Multiple sources of conflict collide as the maniacal Agent Bishop goes to war with the alien forces on Earth, driving the Turtles to embrace unsavory alliances and race to stop a massacre. But this complex web of enemies and allies—as well as new divisions between the Turtles themselves—may thwart any chance they have for success! Collects issues #86-89.

Characters: Aka (TMNT), Alopex, Angel (TMNT), April O'Neil, Baxter Stockman, Casey Jones, Ch'rell, Donatello, Future Donatello, Future Leonardo, Future Michelangelo, Future Raphael, Hamato Yoshi, Harold Lillja, Herman the Hermit Crab, Irma Langinstein, Jennika, John Bishop, Kleve, Leonardo, Libby Meitner, Lindsey Baker, Ma'riell, Master Splinter, Michelangelo, Mondo Gecko, Montuoro, Mouser, Mutagen Man, Old Hob, Pepperoni, Raphael, Ray Fillet, Sally Pride, Sergeant Granitor, Shredder (TMNT), Slash (TMNT), Tang Shen (TMNT), Toad Baron, Traag, Woody Dirkins