Jeff Jacoby has an excellent column on the objections to Gal Gadot being cast as Cleopatra. An excerpt:

Cleopatra VII, the Queen of the Nile, may have been the foremost Egyptian of her day, but she was neither a black African nor an Arab. She was the last of the Ptolemaic Pharaohs, a direct descendant of Ptolemy I, the Macedonian Greek military officer and companion of Alexander the Great who became the ruler of Egypt after Alexander’s death. Though the identity of Cleopatra’s mother has not been definitively established, there is no doubt that Cleopatra regarded herself and was regarded by others as Greek. Egypt today is the most populous Arab country, but there was nothing Arab about Egypt in Cleopatra’s day: The Arab invasion and conquest of North Africa didn’t occur until six centuries after her death….

Applying today’s ethnic labels, Cleopatra would be considered Middle Eastern. Just like Gadot, whose father is a sixth-generation Israeli.

But leave all that aside. Assume for the sake of argument that Cleopatra and Gadot are from two wholly different racial/ethnic categories. Why should that matter? …