Thorkell is a massive Jomsviking general and brother to the Jomsviking Chief. He's basically defined by his love of combat—so much so that he abandons the Danish army to work as a mercenary for the English, figuring that fighting fellow Vikings will give him a proper challenge. That same hunger for battle drives him to back Prince Canute's claim to the Danish throne.
Before things fall apart, Thorkell actually works alongside Thors and respects him deeply, and he's genuinely fond of Thorfinn as the story develops. He faces off against Thorfinn twice in duels, winning both times, though he takes a couple fingers in the first fight and loses an eye in the second. His physical strength is honestly his most terrifying asset—he typically fights with a pair of axes, but fans often note that his raw power is what really sets him apart. During one skirmish with Askeladd's crew, he threw a spear with so much force it went clean through three men at once from hundreds of feet away.
The character draws inspiration from Thorkell the Tall, a historical Jomsviking who served as a mentor to Canute according to the Flateyjarbók.
Content compiled by AnimeList.moe from publicly available sources.