A biblical name meaning 'He that God has given' (i.e. 'God's gift') in Hebrew. This was the name of the prophet who had the courage to reproach King David for arranging the death of Uriah the Hittite in battle, in order to get his wife (Bathsheba). It was also the name of one of David's own sons.
Nowadays Nathan is used as a shortening of Nathaniel or Jonathan. It can be further shortened to simply Nate.
It is also the name of our fearless leader.