Most famous for the surviving fragment attributed to him, “A Hymn to Zeus” in which we find the oldest known version of a teleological argument for God’s existence.
In David Hume’s Dialogues Concerning Natural Religion there is a character named “Cleanthes” who defends the TA and is no doubt based loosely on the 4th Century philosopher.
Read more about Kleanthes.
Read a more detailed account of Kleanthes at the Internet Encyclopedia of Philosophy