Mei-Ling is one of the characters in the Darkstalkers series that's twin sister of Hsien-Ko. Mei-Ling appeared as a cameo in a couple of the Marvel vs. Capcom games.
In Marvel Super Heroes[]
Mei-Ling supports Anita in one of her moves, Lightning Sword.
In Marvel vs. Capcom 3[]
Mei-Ling appears as a human in Hsien-Ko's DLC costume.