Known as Hobbie to his friends, Derek Klivian was branded as the "skeptic" of Rogue Group. During Princess Leia's briefing prior to the Battle of Hoth, Hobbie questioned the effectiveness of a two-starfighter escort for escaping Rebel transports, what with at least one Star Destroyer in orbit. During the Battle of Hoth, Hobbie flew as Rogue Four.
Hobbie was formerly a member of the Imperial Academy. He deserted the service alongside Biggs Darklighter and joined the Rebel Alliance. Circumstances separated the two before the Battle of Yavin. Hobbie was stationed elsewhere when Biggs died in the mission to destroy the first Death Star.
Surviving the Battle of Hoth, Klivian went on to fly with Wedge Antilles in the Battle of Endor. He continued to serve with the legendary Rogue Squadron for years after the destruction of the second Death Star.
In the original script and novelization of The Empire Strikes Back, Hobbie nobly sacrifices himself by plowing his snowspeeder into the head of General Veers' AT-AT walker. This scene is not in the final film, thus sparing Hobbie a fiery end.