Even after Ragnar's death, his sons continued their mission of revenge in Wessex by coming for King Ecbert (Linus Roache) and his people. The group eventually found Ecbert camped out in his deserted castle, ready for his fate. He also came ready with a plan, trading the Vikings' (illegal) land and choosing his own manner of death (suicide in a pool of water.)
After Ragnar's sons banded together to take down King Ecbert, they turned on each other as they continued to squabble about their futures. A provoked Ivar ultimately threw an axe at his brother Sigurd (David Lindstrom) and killed him.
Helga had never gotten over her daughter's untimely death, so when she and Floki came across a little girl in the Mediterranean, Helga "adopted" her as her own. Unfortunately Tanaruz never asked for such a life and in the end she saw no other way out than to kill her adoptive mother. And so she plunged a knife into Helga's neck in the fourth season finale, "The Reckoning" before turning the blade on herself.
Once the greedy king executed Ragnar and drew out his death in the most painful way possible (for a Christian, anyhow), it was only a matter of time before Ragnar's sons came looking for him. They certainly found him in season four's penultimate episode, "On The Eve." Proud, arrogant and underestimating of the viking need for revenge, Aelle easily lost on the battlefield when he was greeted by an overwhelming army. Then, after being forced to show the sons Ragnar's "grave," Bjorn gave him the gruesome Blood Eagle treatment while the other sons looked on.
Arguably the most shocking death in the show's entire run thus far, leading man Ragnar was killed off midway through season four. But even in his final moments, Ragnar found a way to die on his own terms. After he and his men were marooned during a trip to Wessex to get revenge on King Ecbert, Ragnar struck a deal with his archenemy to save his son's life. Although Ragnar publicly told Ecbert he would tell his sons to seek revenge with instead with King Aelle, Ragnar secretly told his son to target Ecbert right before he was dropped into a pit of poisonous snakes.
After losing her husband, Ragnar, and her entire world to the princess Aslaug way back in the show’s second season, Lagertha finally got her revenge in season four. She stormed back into Kattegat while Ragnar and her son Bjorn were away and shot her nemesis in the back with an arrow. Although Aslaug attempted to bargain her way to safe passage by reminding Lagertha that her four sons would avenge her death, Aslaug's pleas weren't enough to change Lagertha's mind.
Erlendur never got over the death of his father, King Horik, and swore vengeance on Ragnar. In order to obtain this, he eventually teamed up with Kalf to kill Ragnar’s son, Bjorn, while he was on a walkabout, but it backfired miserably. Bjorn suspected Erlendur from the beginning, but hid it and stole his wife, Torvi, instead. In Paris, Erlendur attempted to convince Torvi that she needed to kill Bjorn on orders of the Gods, but at the last minute she turned and fired the crossbow at Erlendur instead in season four.
As a slave and new character in season four, Yidu quickly became a venue for Ragnar to work out his guilt and issues. Unfortunately she also provided him with drugs in order to stay alive and useful to him, creating a co-dependency that Ragnar wanted none of by the end. By the time the leader realized he was hooked on this “medicine” and that Yidu was holding his confidences over him, he felt he had no other choice than to drown her in the river while two of his sons watched, nearby.
The unstable Mercia leader had nowhere left to go when King Ecbert took over her lands for himself. But when he forced Kwenthrith and her son (also the son of Ragnar) to stay behind in Wessex, she could take no more and attempted to assassinate the king in his bed. It was only then that his lover Judith came to the rescue, officially getting blood on her hands as she stabbed the former ruler. “Look what you made me do,” she mused softly to the king before the season four scene cut to black.
Although Kalf may have been Lagertha’s next great love after Ragnar, he ruined her trust when he stole her Earldom out from under her. The duo shared a genuine affection, but always knew their time was limited because of that betrayal. In the fourth season, after Lagertha revealed a new pregnancy with the man, they decided to rule together and get married. Unfortunately for Kalf, Lagertha made good on her promise to kill him on their wedding day, when she stabbed him with a knife before their nuptials could be solidified.
Floki and Helga’s daughter was a blessing, but one Floki could never deal with. Her birth caused his own darkness to surface in earnest, leading to marital problems for the couple. Although Angrboda was raised away from Kattegat, she was often seen with the other children, right up until her off-screen demise in season four while Floki was imprisoned. Her death was part of the catalyst that led Ragnar to release finally Floki and allow him to continue raiding with the group.
As Rollo’s lieutenant in the Frankia camp, Eirik stayed behind with the discontented Viking after Ragnar and co. returned to Kattegat. In the season four premiere, he was seen questioning Rollo’s intentions in Frankia and what would happen when Ragnar returned. He was rewarded by Rollo when the traitor rode into camp with the Frenchmen, who open fired with crossbows and killed everyone left.
Athelstan began as a minor character but quickly took on a life of his own when religion became a central theme to the show and its leading man Ragnar. As Ragnar’s beloved right-hand man, Athelstan not only provided knowledge for raids but invaluable advice for Ragnar. This led to jealousy on Floki’s part, who believed the pagan Gods wanted him to kill Athelstan and set his Norse leader back on the right track. After several close encounters over the years, Athelstan finally met his demise at the hands of Floki in season three. His character continues to pop up and haunt the others in visions and dreams with brief appearances.
Siggy may have started out as the wife of an Earl, but when Ragnar killed her husband, she proved to have one strong head on her shoulders and threw herself at the new earl’s feet. Throughout the regime changes she managed to stay alive and provide a voice of reason for first Lagertha and then Aslaug. But when Harbard came to Kattegat in the third season, he supposedly helped relieve Siggy of her misery and mourning (dead children and husband), by leading her to save Aslaug’s sons from drowning in the chilly waters and sacrificing herself instead.
As far as noble characters go, Torstein ranks among the highest. His loyalty to Ragnar never waivered, and his distrust of Rollo continued to be apparent until the very end. After faking his own death in a bid to oust King Horik, Torstein continued fighting for Ragnar right up until he lost his arm in battle at Wessex. He then volunteered himself as a scout for an impossible battle, sacrificing himself to raining down arrows in season three in order to give his friends the best possible chance at winning.
The King of the Danes developed a fast — if not duplicitous — relationship with Ragnar from the beginning. Not only was Horik the one who convinced Ragnar to cut Jarl Borg out the English raids (solidifying another enemy), but he eventually grew mad and attempted to overthrow Ragnar as well. After believing to have turned Ragnar’s men at the end of the second season, it became clear that Floki had never waivered at all and it was all a giant ruse to get the King alone and kill him. Ragnar crushing in Horik’s skull with a rock not only put an end to the madness, but it elevated him to the status of king.
The Vikings were known for their violence and gruesome deaths, but there was none so gruesome as the “blood eagle,” in which the victim’s back is hacked open and his lungs extracted so that he may suffocate without the support of his diaphragm. That’s exactly the fate that Jarl Borg suffered in the second season after betraying Ragnar yet again, and to this day it remains the bloodiest death in the show’s history.
Lagertha’s second husband was ruthless at best, constantly belittling his wife and her son while abusing his power over them. Towards the end of the second season, it’s clear that Lagertha has had enough of the treatment. After Sigvard sent some of his men to her room to beat her and potentially rape her, he capped it all off by baring her breasts to his followers. She responded with a good old fashioned knife in the eye, gaining the respect of everyone in the hall and boosting her to official earldom.
A loyal friend of Ragnar’s from the beginning, Arne was among the first Vikings to head to England and a skilled warrior with the bow. When Rollo first sided with Jarl Borg in the second season however, it all came down to an epic battle between Rollo and Arne. In the end, it was Arne who winded up impaled by Rollo’s spear and then lifted into the sky by the deranged warrior. It was one of Rollo’s biggest betrayals to date, but it wouldn’t be his last.
Ragnar’s daughter wasn’t meant for long in the Vikings world, but when the plague took her while Ragnar was off warring in season one, it left Lagertha devastated. For a long while the shield maiden had been trying to give Ragnar the second son he so desperately wanted with no luck. This led Ragnar to one of his many obsessive states, so it was surprising when he peeled back upon learning of his daughter’s death and appeared to grieve her after all.
A jealous man from the beginning, Haroldson was always wary of Ragnar’s ambitions and desires to raid, believing he only wanted fame and power. Perhaps there was some truth to that, as after several schemes and plots to kill Ragnar and strip him of his life, Haroldson was finally forced to fight Ragnar when the latter challenged him to a dual in season one. As Haroldson lay dying, there was a sense that he was glad to finally be reunited with his dead sons, who were brutally killed long before the series began.
King Aelle’s (Ivan Kaye) brother met his demise when his Northumbria army ran into the Vikings back in the first season's seventh episode. He was kidnapped by the Northmen while sleeping at a camp nearby and used as a bargaining chip with the King. When Aelle went back on his word after negotiations though, Ragnar delivered Aethelwulf’s corpse to the king instead, proving he’s not someone to be messed with.
Technically, Erik was the catalyst that started Ragnar’s eventual ascent to power all the way back in the first season. Not only did he help the future king assemble his team of raiders in secret from Earl Haraldson, but he was eventually assassinated for his part in Ragnar’s raids. Upon his death, Ragnar swore on the God Odin that he would avenge his friend, leading him to eventually kill and usurp the Earl.
As one of Earl Haraldson’s spies, Knut set sail with Ragnar to raid the West and keep tabs on the Viking in case he stepped out of line. When Lagertha attempted to stop him from raping a mother and became an almost rape victim herself, however, she was forced to kill him with no witnesses in season one. This led to a trial back home in Kattegat in which Ragnar shouldered the blame, but was eventually saved by his brother Rollo, who pretended to be a witness to the events, despite a bribe from Haraldson.