He is a sardonic, wisecracking personality matrix downloaded to a robot shell.TOM was originally custodian of the Absolution; alongside its A.I. SARA, his responsibilities include maintaining the ship 
his appearance 
 He has a blue circular light on each side of his rib cage. His body and helmet are gray and his armor plating has a highly-reflective gloss finish. His head is kinda like a biker helmet His visor is  large, plus he has no mouth. taking up a large portion of his helmet.