William Richard Le Fanu (24 February 1816 – 8 September 1894) was an Irish railway engineer and Commissioner of Public Works.
Le Fanu was born at the Royal Hibernian Military School in Dublin into a literary family of Huguenot, Irish and English descent.
He was apprenticed to and became assistant to Sir John Benjamin Macneill.
In 1846 he was appointed resident engineer in the completion of the Cork railway terminal.
He then succeeded MacNeill as consulting engineer to the railway and supervised various line extensions including those to Roscrea, Parsonstown and Nenagh.