Who was the guardian of Cleopatra?

Cleopatra needed no guardian, except perhaps when she was a little child. However you could say that Julius Caesar was her guardian in a sense, because he established her on the throne and made it clear to the Egyptian people that Rome was backing her. But, Cleopatra, because she was a woman did need to have a male co-ruler under Egyptian law/custom. Her marriages to her brothers ended in the brothers dying, so she made her baby Caesarion her co-ruler.