Sweeney Todd.

Pearl-Pearl.

Daniel Plainview.

Marla Grayson.

Strange Supreme (in his debut episode).

Tom Ripley

Jade Wesker

Walter White

Persephone Rosi

Joe Goldberg

Anakin Skywalker (technically)

James Earl Cash in Manhunt

Louis Bloom in Nightcrawler

Leopold II King Leopold's Soliloquy

Barracuda in Punisher Presents: Barracuda MAX

Jack in The House Jack Built

Anakin Skywalker (truthfully)

Arthur Fleck (the Joker)

John Kramer (Saw X really)

Captain Phasma (she was the titular main protagonist in the novel Phasma)

President Snow (Ballad of Songbirds & Snakes)

Andrew Detmer (Chronicle)

Magneto (X-Men: First Class)

He's the main character of first class, watch the movie again, I guarantee you'll see it

MCU!Thanos has been argued to the main protagonist of Avengers: Infinity War.