由 Cartoon, I'll take it as talking about Western 动画片 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. 夏洛特 Magne from Hazbin Hotel. Ty Lee from Avatar: The Last Airbender. Korra from Avatar: The Legend of Korra. 彩虹 Dash, Pinkie Pie and the Dazzlings from My Little Pony. 星, 星级 蝴蝶 from 星, 星级 vs. the Forces of Evil. Ahsoka Tano from 星, 星级 Wars. Bridgette, Lindsay, Zoey and Dawn from Total Drama. Karai and April O'Neil from Teenage Mutant Ninja Turtles. Miko Nakadai from 变形金刚 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.