What do you call a fixed male cat?

He is still called a Tom Cat. Females are called Queens.

gib (gb)

NOUN:

: A male cat, especially a castrated one. Yahoo.com/reference/dictionary/entry/gib_2;_ylt=AjYR5eQ7LDxsIyrG9UYf3_GugMMF">http://education.Yahoo.com/reference/dictionary/entry/gib_2;_ylt=AjYR5eQ7LDxsIyrG9UYf3_GugMMF