Mark Ruffalo stars as both leads in I Know This Much Is True, the new series on HBO.

It's a six-part limited series that will debut on April 27. Ruffalo portrays twin brothers who are forced to confront their difficult past.

Mark Ruffalo as twins in HBO's I Know This Much Is True

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HBO's I Know This Much Is True: What we know so far

I Know This Much Is True is an adaptation of a book by author Wally Lamb.

The series follows "Dominik," who is forced to care for his twin brother, "Thomas," a paranoid schizophrenic, after a violent incident. Ruffalo plays the role of both twins in the show.

It is directed by Derek Cianfrance, who is known for the well-received films Blue Valentine and The Place Beyond the Pines - which both starred Ryan Gosling.

Mark Ruffalo and Derek Cianfrance at the TCA Winter Tour 2020 for HBO's I Know This Much Is True.

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Mark Ruffalo: Movies and roles post-Avengers and "Hulk"

Ruffalo wrapped filming on Avengers: Endgame in 2019. It now seems he'll be able to work on new projects after multiple "Hulk" roles in a short period of time.

But he is set to voice "Bruce Banner" ("Hulk") in the Disney+ animated series, What If...? in 2021.

He's also rumoured to be attached to the HBO adaptation of Best Picture-winner Parasite

See twice as much Mark Ruffalo as you're used to in I Know This Much Is True when it debuts on April 27!