Yarbog was an Urgal ram who challenged Roran for control of the company during a raid in Brisingr. He also fought in the Siege of Feinster. It is unknown if he survived, as he is never mentioned again, save for a flashback to his wrestle with Roran.
When Yarbog was under Roran's command, Yarbog and a couple fellow Urgals tied an enemy soldier to a tree and started poking him with a sword. This infuriated Roran, who then killed the soldier and put him out of his misery. Yarbog then went on to disobey Roran and then challenged him to wrestle. Eventually he lost to Roran and became disgraced. When Roran defeated him, he asked Roran to kill him but Roran told him it was not his role: if he was going to die, it would be at the hands of the Broddring Empire.
Yarbog does not take orders well, from any high rank soldier. However, that just may be because he is an Urgal and his leaders are humans in the Varden. He is very proud of his horns, as with any Urgal, but lost almost all self-respect after wrestling Roran.