Mileena made her debut in Mortal Kombat II (1993). Mileena is a clone of the game's main female character, Kitana, created by the sorcerer Shang Tsung. She has a half-Tarkatan, half-Edenian heritage, which gives her a unique appearance with a mix of human and monstrous features.

Mileena is known for her fierce and aggressive fighting style, as well as her iconic weapon, the sai. She possesses superhuman strength, agility, and speed, making her a formidable opponent in combat. One of her most notable abilities is her sharp and retractable Tarkatan teeth, which she uses as a weapon.

In the Mortal Kombat storyline, Mileena has a complex and conflicted relationship with Kitana, often serving as a rival and enemy. She has appeared in multiple Mortal Kombat games and spin-off media, becoming one of the series' most recognizable and popular characters due to her unique appearance and fierce personality.