Jack Fisk is a fictional character from the 2004 TV series Battlestar Galactica, portrayed by Graham Beckel.Jack Fisk, service number 245A-34DC, was originally a Lieutenant Colonel (later Colonel) aboard the Battlestar Pegasus and was the Executive Officer (XO) of the vessel, serving under the command of Admiral Helena Cain. Fisk was first encountered when the refugee fleet discovered the Pegasus, learning the ship had survived the Cylon attack on the colonies.