Askeladd (アシェラッド, Asheraddo) also known as Lucius Artorius Castus, was a cunning, mysterious Viking who commanded a mercenary band of Vikings that included Thorfinn. Askeladd was half Danish and half Welsh, claiming descent from the legendary Lucius Artorius Castus, for whom he was named by his mother, with "Askeladd" being a nickname.
He was contracted by Floki to assassinate Thors and shortly after took Thorfinn in, who grew up on the battlefield and became obsessed with avenging his father's death by killing his commander. After his band was wiped out by Thorkell, Askeladd pledged his service to Canute to achieve this goal of keeping Wales safe from Viking invasion.
Askeladd is an average-sized Viking warrior. He is very strong, demonstrating himself capable of bisecting a man in full armor with his sword. Being half-Welsh and half-Danish, he has blond hair. His face features a small beard that goes just around his mouth, with sharp and cunning eyes. He used a dark heavy breastplate more reminiscent of the Roman tradition.
Although Askeladd sometimes wants to give the impression of being weak, old, or not in control of his troops to his enemies, he's the exact opposite. He uses deception to give a false sense of 'we-can-win-this-no-problem'. Then to surprise them and take advantage of their momentary loss of sense and order to bring them down.
Master swordsman: Askeladd was a highly skilled swordsman, displaying a talent for this at age 11 when he defended his mother from attack from his father Olaf. Despite being middle aged at the time of his death, he survived combat against multiple opponents at once, including Sweyn Forkbeard's royal guard.
Ranged weapons: Askeladd had skill with throwing hatchets and throwing knives, although they were not his primary weapons.
Askeladd is also a master tactician as well as a skilled politician. His ability to manipulate those around him turned a horde of pirates and raiders into a close-knit group wholly loyal to him. He has shown himself capable of turning enemies into allies, as seen with Thorfinn, Thorkell, and Prince Canute.
Askeladd could also quickly instantly read a man, an ability he claimed that to have picked up from living 40 years among wicked men.
Askeladd is the son of Lydia, a Welsh noblewoman who was captured and enslaved by his Viking father Olaf. He has several half-brothers who Olaf had with his legitimate wife and an unknown number of bastard half-siblings. Although Lydia was Olaf's favorite for some years, when her health failed she was relegated to the stables and thus Askeladd had to work from a very young age to provide for them both.
Witnessing how his mother and her people was mistreated by the Norse and the English, Askeladd despises his Scandinavian heritage and embraces the Romano-Celtic heritage of his mother, although, he is nevertheless shown to be a believer in the Norse gods. Sharing the belief of Welsh people, Askeladd longs for the day when his King Artorius would return and liberate the Briton people from the Germanic oppression. However upon encounter with Prince Canute, he realizes that belief is nothing more than a fairy tale and decides to aid Canute in the greatest cause.
Askeladd's role in the series is the captain of a notorious band of Viking pirates. He is the unlawful murderer of Thors. He's Thorfinn's 'boss' even though Thorfinn rarely listens to him, apart from when he gets a chance to fight Askeladd (his usual reward). He is a mentor for Thorfinn and a catalyst that brings about the change in Canute.