Which character does Shrek seek to find as heir to Far Far Away in Shrek the Third?

In Shrek the Third, Shrek seeks to find Arthur Pendragon as heir to Far Far Away.

After King Harold dies, Shrek is expected to become the next ruler because he is married to Princess Fiona. Shrek dislikes the idea of being king, so Harold’s adviser Merlin identifies Arthur, Harold’s teenage nephew, as the proper remaining heir.

Shrek, Donkey, and Puss in Boots travel to Worcestershire Academy to bring Arthur back. Arthur begins as an insecure student but eventually accepts his responsibilities. The character draws on the legendary King Arthur tradition, although the film presents this Arthur as a modern teenager within its comic fairy-tale setting.