Rear Admiral Sir Robert Keith Arbuthnot, 4th Baronet, KCB, MVO (23 March 1864 – 31 May 1916) was a Royal Navy officer during the First World War.

Upon acquiring command rank, Arbuthnot quickly developed a reputation as a dedicated but highly inflexible and detail-obsessed martinet, with a passion for "the highest authoritarian standard of discipline, mercilessly enforced.

"[7] Even by the strict disciplinary standards of the Royal Navy, Arbuthnot's zeal was unusual; in 1900 as executive officer of Royal Sovereign, Arbuthnot wrote and published A Battleship Commander's Order Book, containing some 300 pages of detailed standing orders for his crew, when a ship's Commander at this time would typically produce just a few pages of special instructions to act as an addendum to the standardized King's Regulations procedural manual.

While the book remains a valuable source of historical information on details of life aboard a battleship at this time, it made Arbuthnot the butt of so many jokes from his contemporaries that he later allegedly requested it not be mentioned in his biographical entry in Who's Who in the Navy.

[8] Aside from his love of discipline, he also continued his obsession with physical and spiritual fitness, spending several hours each day performing strenuous exercises on deck, rain or shine, attending daily church services and lecturing his crew on Christian virtue.

Although largely regarded with bemused admiration by his superiors and respectful fear by his subordinates, his extreme nature caused some to consider him a fanatic; Andrew Gordon describes him as "in a colloquial if not a clinical sense, insane.

By the time Warrender (attending to other aspects of the battle in HMS King George V) realized the cause of Arbuthnot's reticence and had the order hoisted, the ships had already turned away and escaped.

[16] Arbuthnot's goal was apparently aggressively to close at high speed with the drifting, crippled German light cruiser Wiesbaden in order to finish her off.

At the first glance I recognise an old English armoured cruiser and give the necessary orders...Range 76 hm....Five salvoes rapidly follow, of which three straddle: then there was repeated the now familiar sight of a ship blowing up.

She was unintentionally saved from impending destruction by the super-dreadnought HMS Warspite, which was forced to turn in circles around Warrior because of a stuck rudder, drawing the enemy fire to herself in the process.

Black Prince was blown up with the loss of all hands that night after blundering into the main German battle line in the dark, leaving Duke of Edinburgh as the sole vessel in 1st Cruiser Squadron to survive Jutland.

[20] Walter Cowan, captain of the battlecruiser HMS Princess Royal saw the cruisers approaching the German fleet and commented he would "bet anything" it was Arbuthnot.

[21] A memorial plaque was erected to Arbuthnot in St. Giles' Cathedral, Edinburgh,[22] and he was posthumously appointed a Knight Commander of the Order of the Bath, having been made a Companion already in 1916.