zangetsuZangetsu is the manifeste spirit of Ichigo Kurosaki's Zanpakuto, and is often shown as a 40-50 year old man with a scruffy face and ragged, long black hair, wearing tattered black clothes and sunglasses, as well as his large, flowing overcoat. He is first seen when Ichigo travels into his inner world to find the strength to fight against himself turning into a Hollow. He often gives Ichigo a lot of smack talk and puts him through the ring, but it's to make him strong.
Zangetsu's personality is even-tempered, a stark contrast to the temper of his master, and he often acts as a mentor to Ichigo in his times of need. Zangetsu is one of the most unique Zanpakuto, as shown in the Zanpakuto Rebellion when he says that he doesn't wish to leave Ichigo, but is fighting him to see him get better.
BankaiTensa Zangetsu, Ichigo's Bankai, is a bit different than his original form, being a younger and wearing a hooded cloak instead of a long coat. His personality is still calm and collected, but is far more aggressive, as shown by him dominating the control when he and Hollow Ichigo fuse.
Though he's prone to occassional outbursts, he tends to be much more calm than the Hollow itself, even though they're more alike than his original form.