Flyboy is, presumably, the callsign for a Viper pilot on the Battlestar Galactica.
He was under Captain Lee Adama's command and, along with Kat, protected Captain Adama as he attempted to destroy a Cylon troop transport. (Scattered) Flyboy can be very wreckless, and jokes a lot in the cockpit, even in dire situations. He was killed by Cylon Centurions in Valley of Darkness.