For his portrayal of which famous comic book character did Joaquin Phoenix win an Academy Award for Best Actor?

Which famous musician did Joaquin Phoenix portray in the acclaimed 2005 film Walk The Line?

Which famous historical person is Joaquin Phoenix set to portray on the screen in an upcoming film directed by Ridley Scott?

Commodus was a Roman emperor who ruled from 177 to 192. He served jointly with his father Marcus Aurelius from 176 until the latter's death in 180, and thereafter he reigned alone until his assassination. In which historical fiction film did Phoenix portray this character?

In this acclaimed 2013 film, Joaquin Phoenix portrays a character who develops a relationship with Samantha (Scarlett Johansson), an artificially intelligent virtual assistant personified through a female voice. Name the film.