Name: Clayface
Aliases: John, Walter, Emma, Donna, probably others...
Age: impossible to tell
Physical Description: In its natural form, Clayface is a hulking, top-heavy 7' tall humanoid creature, comprised entirely of a brown mud-like substance.  It is mostly featureless aside from rough skin and hollow, sunken eyes.  It is an omnimorph, capable of altering its form to nearly limitless shapes and colors.
It takes a normal human form, depending on which personality is dominant at the time.  The most common ones:

• John - average young adult white male
  
• Walter - elderly black man, unshaven and in glasses
  
• Emma - precocious 5-year-old girl with strawberry blonde hair.  Usually carries a teddy bear.
  
• Donna - middle-aged Latina woman

Biography: Clayface exhibits multiple personality disorder, to a much more extreme, unsubtle degree.  It also suffers low-grade amnesia - most often the personalities are aware of what the dominant one is doing, but any long-term memories are a jumbled mess and are likely fabrications, save for repeated exposure or anything traumatic.  Usually the personalities shift based on emotional reactions, though with enough concentration it can maintain a single form for a length of time.  It can take the appearance of someone else it sees (even mimicking their voice, which it avoids if it can due to being a poor impressionist), which it has used to great effect to steal supplies from the Wasteland raiders on the behalf of its fellow mutant outcasts.
Clayface hates its condition, referring to its natural form as "the creature", but has also begrudgingly accepted its usefulness in spite of the mental difficulties.
Due to its condition, Clayface is capable of incredible strength and agility.


History: It doesn't remember anything from before the bombs, though really it's lucky if it can remember what happened last week.  The best it can surmise is that it's a combination of faulty medical nanobots and good old-fashioned mutation from the radiation that caused its condition.  Those nanites are what are keeping its fragile psyche intact, as well as taking care of whatever other functions are necessary due to its lack of internal organs.