The (Big) Mobile Armored Computerized Combatant, or (Big) MACC (spoken out as "(Big) Mack"), is a character from the 1987 TV series episode "Attack of Big MACC." During an electrical storm, he exited from a time vortex and was immediately confronted by armed soldiers, whom he defeated easily.
Krang wanted to capture the robot for his own ends, so he sent Shredder, Rocksteady and Bebop to the surface. After a rocky start with the Turtles, Michelangelo managed to befriend MACC and rescue April. However, MACC is almost immediately captured by Shredder, who places a Docilator on him in order to control him. However, he was able to swat the Docilator off, and began shooting at the three villains.
MACC explains that he was put off by Shredder's demands that he kill the Turtles, and that he was a factory reject because of his dislike for violence. After an interview with April (and a conversation with a TV camera which he mistook for his brother, Number 5), the Turtles bring him to the public library, where MACC "inputs data" from the books.
Back in their lair, MACC is introduced to Splinter, but also starts deteriorating physically, which means that he will eventually blow up. To keep his new friends safe, MACC decides to disappear. As he roams the sewers, Shredder catches him, places another Docilator on him and sends him on a rampage.
Krang attempted to use MACC to bring more futuristic robots into the present, but the Docilator is shaken off once again, allowing him to free the Turtles and dispose of Shredder and his minions. A time portal is opened, and MACC reluctantly agrees to return after Donatello advises him to be a "warrior for peace" in his own time.
Despite claiming to detest violence, he immediately attacks anything that causes violence. He likes to speak like a cowboy from Western movies, much to the chagrin of the Turtles and Krang.