Captain Hamstern is captain of Team Seahams is a pirate. He appears in the Hamtaro Ham-Ham Games GBA game, Hamtaro Movie 3: Miracle in Aurora Valley, and the Ham-Ham Games OVA (mentioned). In the show, he is called Captain Hamcook. His japanese name is probably allusion to Captain Hook from Peter Pan. His english name is from the word Hamster and Stern, refering to his serious personality.
Hamstern and his crew first made appearance to kidnap Bijou and prevent her from bringing snow back to Aurora Valley.