mixed question, yes and at the same time a huge, resounding no.
the basic deity of Wicca is the Horned God and Triple Goddess, which basically these two are merely stages in the year, spring, summer, winter. you don't have to believe in any deities if you feel you don't. some people believe there's this giant ball of energy that we return to after death to tell of the lessons we learned in this lifetime.
certain spells work better when calling upon certain deities because that's their specialty. [example Aphrodite for love] the third option people have, most people do in fact, is choose two deities from other cultures to act act their God and Goddess. i do know of people who have no deity, believing that it's really nature one must worship, others focus on only one god or goddess [personally i don't see why, there's two for a reason, everyone has male and female in their lives, but whatever, your faith] finally, there are people who pray to creatures, elements, or mythical beings. myself while i do have a God and Goddess i pray to, i follow Dragon Magick, so i call upon dragons the same way someone would call upon their deities.
my point is, it's all personal faith, whatever feels right for you is the right answer. hope that helped.