Mileena is a character in the Mortal Kombat series. One of the most popular female character of the franchise, primarily due to her strikingly seductive overall appearance in contrast to her large, sharp-toothed mouth which she usually covers up with her mask.
In her previous portrayals, Mileena is depicted as an antagonistic sisterly figure of Kitana, with her origin varying between each incarnations. In the first two timelines, she is depicted as a botched clone of Kitana specifically ordered by Shao Kahn to be served as a "substitute" of Kitana in case his adopted daughter found out about the truth of her origins.
In the third timeline meanwhile, Mileena is depicted as the biological older sister of Kitana, though she has been infected by a virus known as 'Tarkat', which disfigured her lower face and often causes her to go on a rampage in the event she had not periodically taken the serum needed to control it. She's re-characterized as the confident-yet-noble heir apparent of the Outworld throne, and is capable of keeping her fully human appearance with the use of the aforementioned serum.