"Mr. White" is an artifact costume in the StrikeForce Kitty series, based on Fire Mario.
StrikeForce Kitty 2
"artifact 16" can be equipped to a kitten that wears either the "Plumber" or "Brer" cosplay. "Mr. White" does 
ranged damage, in reference to the games, and has the same passive ability as the kitten wearing either cosplay.
"Mr. White" adds 9 strength, 3 health, and 6 speed to that kitten, for a total of 37 strength, 22 health, and 19 speed, from "Plumber", and 28 strength, 28 health, and 25 speed, from "Brer".
Notes: Even though "Brer" references Luigi, it still transforms into Fire Mario, not "Fire Luigi" as intended. Also, there is no bottom part of the overalls or shoes, the same with "Pupil of Shao Kahn", it may be a bug.
StrikeForce Kitty: Last Stand
Fire Mario in Last Stand
Fireball in Last Stand
"Mr. White" is a cosplay that can be obtained from defeated raccoons in StrikeForce Kitty: Last Stand, look on pages in the 
"Ranged" category. Unlike in StrikeForce Kitty 2, the bottom of the overalls and shoes do appear.