Simon Marlow, Haskell enthusiast, GHC boiler-room technician

Simon is "The Other Simon", where the other Other Simon is Simon Peyton-Jones. For a long time, there was a standing joke in the Haskell community that if something would happen to the Two Simons, it would be a disaster for Haskell. Simon P-J maintains the GHC Haskell Compiler and Simon Marlow maintains the Haskell Runtime.