While TMNT was made mainstream through the 1987 TV series, it began as a comic in 1984. The TMNT comic was dark and gritty, featuring a no-nonsense group of turtles that in no way resembled their super-friendly an rarely-serious counterparts from the 1987 animated series.
In 1984, Eastman and Laird brought to life a group of unlikely heroes that in fact started off as a joke (turtles, not exactly known for their speed, stealth, or fighting prowess, made dubious candidates for a group of crime-fighting ninjas).
To this day, TMNT comics continue to provide readers with endless entertainment. As of this writing, there is even talk of a new TMNT comic, so keep eyes out for this!