Tom Hiddleston's Loki has played almost as much a role in the Marvel Cinematic Universe, as the heroes whose names grace multiple solo films. Long considered among if not the MCU's best villain, Loki has betrayed Asgard, tried to have his brother killed, impersonated Odin and invaded Earth. Loki was the antagonist that provided the need for the Avengers to assemble in the first place.
So all in all, the God of Mischief hasn't been the best dude in his five MCU appearances. But actor Tom Hiddleston believes that Loki finally redeemed himself during Avengers: Infinity War, as he explained at ACE Comic Con:
I think the first film really humanizes him and I think makes the rest of the journey interesting. It makes you always think that he could be pulled back and redeemed. And in my opinion, he is redeemed in Infinity War.
In his comments at ACE Comic Con (via Comicbook.com), Tom Hiddleston seems to view Loki's arc from his first appearance to his last as a big part of what redeems the character. He is redeemable in the first place because we saw his humanity before he became a villain in the original Thor.
Loki isn't Voldemort who was rotten and chose evil from the start; he was just an innocent baby like any other, and then an adult who found out too late, in a terrible way, about his true origin story. In his pain and confusion, he lashed out and did terrible things. For Tom Hiddleston, Loki was redeemable because we knew why he did what he did and that he wasn't always a villain and that somehow, some way, he could find his way back to that place.
And Tom Hiddleston was right. Over the course of his MCU arc, Loki went from villain to frenemy to the point where he was at in Avengers: Infinity War, where he could have a real relationship with his brother and be redeemed. In Infinity War, Loki gets his Darth Vader in Return of the Jedi moment, where he chooses heroism and redemption, making a last ditch effort to kill Thanos. Unlike Anakin, he fails, but it is the choice he makes that redeems him.
What hammers it home, too, for the audience is that prior to his death, when listing his titles to Thanos, Loki calls himself "Odinson" and looks at Thor. This shows that after feeling betrayed by his adoptive father in Thor, Loki has finally come back around to the point that he mourns his father's passing and takes pride in the surname.
This doesn't necessarily take away from the lives lost because of Loki's actions, but as Stannis Baratheon once said, "A good act does not wash out the bad, nor a bad act the good." Loki's villainy has also gained some complexity recently when Marvel changed his official bio to confirm that during 2012's Avengers he was being influenced by the Mind Stone in the Scepter. He had the negative impulses already, but he may not have acted on them to such a degree without that corruption.
Loki's redemption may not be finished either, or at least his story isn't. Tom Hiddleston will be starring as the character in a limited series for the upcoming Disney+ streaming service. We don't yet know what that will be about specifically, but no one will complain about more of this complex and entertaining character.