Upvote:4
Thucydides and Xenophon.
And if you can sacrifice some credibility for entertainment, Herodotus.
Also, not historians but I really recommend reading Homer, Hesiod, Aeschylus, Sophocles and Euripides to get a grasp of their world.
Modern historians specialized in Ancient Greece I've only read Donald Kagan and Luciano Canfora.
EDIT:
Wikipedia Category Scholars of ancient Greek history has 43 names of modern historians in it.