Chef Ham (コックさん, Kokku-san/Cook-san) is a chef hamster with a colourful Italian accent and 10 children, the Chibi Hams.
Chef Ham is a chef that visited the Ham-Hams. They were happy when he arrived (especially Oxnard) so they could have a huge feast! Chef Ham has travelled the globe cooking for hamsters. When he came back from his travels, he was supposed to make a feast for his kids, but he was afraid to cook for them (fearing they wouldn't like it), so the Ham-Hams decided to have the party at the clubhouse.
His homeland is Italy. He loves to dance and sing while he cooks. Hamtaro referred to him as a 'grown up', so he is most likely older than the Ham-Hams.
See also: Chef-Ham/Gallery