Just like any form of media, anime doesn't only portray the good and the just. It is especially not necessary for the plot to use the hero's perspective to be good. Antihero protagonists like Eren Jaeger from Attack on Titan and Ken Kaneki from Tokyo Ghoul are prime examples of this.
As it rises in popularity each passing year, the isekai genre has also delved into this theme and has produced numerous anime focusing on the bad side's perspective. Here are the best isekai anime whose main character is a villain, in different senses of the word.
Overlord Stars a Classic Villain
After being trapped in his favorite RPG, Overlord's main character, Momonga, assumes his role as a monster dungeon master. He rules over his domain and allows his subordinates, who are various kinds of monsters, to do what they do best. Some of their activities include human experimentation, massacre and abduction.
Interestingly, Momonga still attempts to do altruistic deeds whenever he can, giving the anime a whiff of lightheartedness. Viewers will be taken on a rollercoaster of emotions as they witness Momonga and his subordinates expand their territory.
Reincarnated as a Slime's Rimuru Does Villainous Acts for His Constituents
That Time I Got Reincarnated as a Slime protagonist Rimuru Tempest is a chill character who wishes to enjoy his new isekai life -- until so-called heroes bring the worst out of him. Rimuru may have unintentionally grown his kingdom, but he genuinely cares for his constituents.
That is why he went berserk after some of his subordinates were mercilessly killed. He even reaches the point of committing genocide in order to become a demon lord and resurrect them. Rimuru's evolution from a slime to a demon lord is proof that even the kindest of creatures have a threshold for goodness.
The Rising of the Shield Hero's Naofumi Is a Framed Villain
The Rising of the Shield Hero's Naofumi Iwatani has gone through a lot not because he's an evil person, but because he is framed to be one. The first member of his party tricks him into accepting her as a member, then betrays and abandons him unprovoked.
Her betrayal forces Naofumi to resort to every dirty trick he knows in order to survive. Worse is that everybody else, including the other heroes, views him as a despicable entity. The Rising of the Shield Hero perfectly demonstrates how anybody can be turned into a villain through lies and theatrics.
Katarina Claes Is Reborn as a Villainess
Katarina Claes from My Next Life as a Villainess: All Routes Lead to Doom! receives the short end of the stick when she one day regains her memories from her previous life. She realizes that she is currently living as the villainess of an otome game she used to play called Fortune Lover. Katarina's attempts to avoid her multiple gruesome deaths results in a funny and chaotic series of events. Despite supposedly being this isekai series' main antagonist, Katarina becomes both the comic relief and the protagonist.
So I'm A Spider, So What? Features A Monster Protagonist
Kumoko, the main character in So I'm a Spider, So What? gets unlucky and is reincarnated as a literal monster while her classmates are humans. Unlike Momonga and Rimuru, however, she isn't anthropomorphic. She's a spider through and through, and her evolutions make her more of a spider -- at least the first ones. Born in a dungeon filled with terrifying and powerful creatures, Kumoko uses everything at her disposal to eliminate threats and defend herself. By doing so, she is also forced to kill numerous humans and is viewed as a terrifying monster -- which she technically is.
The Saga Of Tanya The Evil Is Top Tier Evilness
When it comes to villainy in isekai anime, The Saga of Tanya the Evil can't be forgotten. The titular character assumes the identity of a young girl living in a war-stricken world as punishment for his previous lack of faith. Instead of repenting, Tanya uses her knowledge of war and tactics to rise through the ranks and hopefully earn a cushy position away from the bloodshed. This little girl has no qualms about sacrificing countless lives and manipulating numerous individuals if it means achieving her goal.