There was a fifth, female Teenage Mutant Turtle!

The Teenage Mutant Ninja Turtles were the heroes that the 1990's wanted and deserved. They were fun, butt-kicking mutated turtles who lived in a sewer and took orders from a large, mutated rat.They fought crime, saved the world, and always had time for pizza!

The only problem? The show was such a sausage fest! That was fixed when a live-action TV series based on the turtles introduced a fifth member.

Ninja Turtles: The Next Mutation ran from 1997 to 1998 on Fox Kids and portrayed our heroes as grown up. A fifth, female turtle, named Venus De Milo was mutated at the same time, but washed away in the sewer. She ended up in New York's Chinatown. She ended up in China for 1 years learning the Shinobi arts and then returned to New York.

The show was canceled in the summer of 1998 and marked the first time the Teenage Mutant Ninja Turtles weren't on a TV screen for a protracted period since the original animated series in 1987.

The next animated series began in 2003. It received fairly negative reviews, though some liked the Power Rangers vibe it gave off.

(Source)