Who played Albus Dumbledore before Michael Gambon?

The actor who played Albus Dumbledore before Michael Gambon was Richard Harris.

He portrayed Dumbledore in the first two Harry Potter films:

* Harry Potter and the Sorcerer's Stone (2001)

* Harry Potter and the Chamber of Secrets (2002)

Sadly, Richard Harris passed away in 2002, leading to Michael Gambon taking over the role for the remaining films.