Simon Mark Arthur, 4th Baron Glenarthur (born 7 October 1944), is a British peer, pilot and businessman.

The son of the 3rd Baron Glenarthur, he was born into a Scottish mercantile family and was educated at Eton College.

Between 1976 and 1980, he served as a Major in The Royal Hussars, Territorial and Army Volunteer Reserve, and was Captain for British Airways Helicopters between 1976 and 1982.

From 1977 to 1982, Lord Glenarthur was director of Aberdeen and Texas Corporate Finance Ltd and from 1979 to 1982 for ABTEX Computer Systems Ltd.

[1] Since 2010, Lord Glenarthur has been governor and a trustee of King Edward VII's Hospital Sister Agnes.

In his role as governor, he wrote to the Australian radio station 2Day FM in the wake of their hoax call to the King Edward VII's Hospital concerning the pregnancy of The Duchess of Cambridge, and the subsequent death of nurse Jacintha Saldanha who took the call.