Alan IV (died 13 October 1119) is Duke of Brittany from 1084 until his abdication in 1112.

He is also Count of Nantes and Count of Rennes.

His parents are Hawise, Duchess of Brittany and Hoel II.

He is also known as Alan Fergant.

("Fer gant" in French means "Iron glove".)

Through his father, he is of the Breton House of Cornouaille dynasty (Breton: Kerne dynasty).

He is the last Duke of Brittany to speak the Breton language.