Boy Saves A Baby Fawn, Bangladesh

In the Harry Potter series, the Patronus Charm that Harry Potter conjures to repel Dementors is a silver stag. James Potter, Harry's father, had an Animagus form as a stag. Also, Harry's mother Lily Potter, and subsequently Severus Snape's, Patronus form was a doe.
In one of the stories of Baron Münchhausen, the baron encounters a stag while eating cherries and without ammunition, fires the cherry-pits at the stag with his musket, but it escapes. The next year, the baron encounters a stag with a cherry tree growing from its head; presumably this is the animal he had shot at the previous year.
A Samurai warrior named Honda Tadakatsu famously adorned deer antlers on his helmet.
Deer have been a subject in Chinese paintings numerous times as a tranquility symbol.