Stanley Owen Green (22 February 1915 – 12 December 1993), known as the "Protein Man", was an English human billboard in central London in the latter half of the 20th century.

[2] According to Lynne Truss, Green became such a ubiquitous figure around Oxford Street in the West End that he was "present in every black-and-white picture of London crowds that one has ever seen".

[3] For 25 years, from 1968 until 1993, Green patrolled Oxford Street with a placard recommending "protein wisdom", a low-protein diet that he said would dampen the libido and make people kinder.

[7] The "warm and secret place" was a bench at the far end of one of the platforms at Oxford Circus station, where he would sit after turning his placard upside down and facing the wall.

[7] Sundays were spent at home producing Eight Passion Proteins on his printing press, exhibited after his death at the Serpentine Gallery and described by Waldemar Januszczak as "an extraordinary home-made contraption worthy of Heath Robinson".

[14] It ended by warning: "Beware of the fun of indecent suggestions; of the amusement from the titillating scandal of private lives; of the diversion of the undress of low journalism etcetera.

The Sunday Times interviewed him in 1985 for its "A Life in the Day" feature, and some of his slogans, including "less passion from less protein" were used on dresses and T-shirts by the London fashion house Red or Dead.

[4] His printing press was included in Cornelia Parker's exhibition "The Maybe" (1995) at the Serpentine Gallery, featuring Tilda Swinton in a glass box, as well as a cushion and carpet apparently from Freud's couch and one of Winston Churchill's cigars.

In 2006 he was given an entry in the Oxford Dictionary of National Biography,[1] while the artist Alun Rowlands' documentary fiction, 3 Communiqués (2007), portrayed him as "trawl[ing] the city campaigning for the suppression of desire through diet".

[20] Peter Watts wrote in Londonist in 2016 that Green was for a time "the most famous non-famous person in London, a figure recognised by millions even if few ever actually spoke to him.

"[2] When Green died, Lynne Truss suggested in The Times that he be inserted retroactively into the final paragraph of Charles Dickens' novel Little Dorrit: They went quietly down into the roaring streets, inseparable and blessed; and as they passed along in sunshine and shade, the noisy and the eager, and the arrogant and the forward and the vain, and that man, you know, with the "Less Passion from Less Protein" sign above his head, fretted and chafed, and made their usual uproar.