Super mutants were supposed to be included in Interplay's Fallout MMO, Fallout Online (also referred to as the original Project V13). From a screenshot as proof of concept one could see what seems like a peaceful super mutant. In the short story On the Beach, published in The Armageddon Rag, Vol. 3, the Brotherhood of Steel, working alongside the Guardian Brotherhood, were fighting against seemingly hostile super mutants that had obtained and utilized power armor.
See super mutant for more details of super mutants in the Fallout universe.