HH Prince William Augustus Edward of Saxe-Weimar, KP, GCVO, PC (October 11, 1823 - November 16, 1902) was a British military officer of German ancestry.

Prince Edward was born to Charles Bernard of Saxe-Weimar and Princess Ida of Saxe-Coburg-Meiningen (whose sister Adelaide was King William IV's wife). His military career began in 1841, when he joined the 67th (South Hampshire) Regiment of Foot as an ensign. His royal connections ensured that he proceeded quickly through the ranks, attaining major in the Grenadier Guards on June 20, 1854. He held that brevet rank when he entered the Crimean War, in which he received many battle honours.

Edward received his colonelcy in the Grenadier Guards on October 5, 1855, then proceeded through the general ranks, until he became a full general in 1879. During his military career (in 1851), he married, morganatically, Augusta Katherine Gordon-Lennox , (a daughter of Charles Lennox, 5th Duke of Richmond), who by virtue of her marriage was created Countess of Dornburg , (she was granted the rank of princess in Britain by royal decree of 1866); the couple had no children. His military career reached a pinnacle in 1897, when he was promoted to field marshal, the highest military rank in the British Army. Throughout his military and political career, he received many honours (including the Legion d'Honneur) and served in many positions (including as Commander-in-Chief in Ireland , thereby becoming a member of the Irish Privy Council).