Mel

Originally the Protagonist of Portal 2, Mel would appear as a reskin of Chell's model in Portal 1. She would be a blond female Test Subject that wore a bright blue jumpsuit.

She was cut due to playtester backlash over GLaDOS not recognizing the player and was later replaced as Valve deemed the identity of Portal 2's Protagonist would be better of as Chel.  During Development of the CO-OP mode for Portal 2, she was brought back briefly as a Playable Character alongside Chell. She was cut again and replaced with Atlas and P-Body. 