By Cartoon, I'll take it as talking about Western Animation and excluding Anime. There are quite a few to mention nonetheless.
Harley Quinn is certainly one of them.
Others including:
Starfire from Teen Titans.
Gamora from Guardians of the Galaxy.
Charlotte Magne from Hazbin Hotel.
Ty Lee from Avatar: The Last Airbender.
Korra from Avatar: The Legend of Korra.
Rainbow Dash, Pinkie Pie and the Dazzlings from My Little Pony.
Star Butterfly from Star vs. the Forces of Evil.
Ahsoka Tano from Star Wars.
Bridgette, Lindsay, Zoey and Dawn from Total Drama.
Karai and April O'Neil from Teenage Mutant Ninja Turtles.
Miko Nakadai from Transformers Prime.
Lola Bunny from Looney Tunes.
Jenny Wakeman from My Life As A Teenage Robot.
Jinmay from Super Robot Monkey Team Hyperforce Go!
Go Go Tomago from Big Hero 6.