Did the actor who played Vernon Dursley in Harry Potter also play as King Pirates of Caribbean 4?

You're likely thinking of Richard Griffiths, who played Vernon Dursley in the Harry Potter films. However, he did not appear in any of the Pirates of the Caribbean films.

The character you're referring to, likely from Pirates of the Caribbean: On Stranger Tides, is Blackbeard, played by Ian McShane.

It's an easy mistake to make as both actors have distinct appearances and are well-known for their roles in other films.