According to Dave Wilton, "Some time during the war, Chad and Kilroy met, and in the spirit of Allied unity merged, with the British drawing appearing over the American phrase.

"[2] Other names for the character include Smoe, Clem, Flywheel, Private Snoops, Overby, Eugene the Jeep, Scabooch, and Sapo.

The phrase may have originated through United States servicemen who would draw the picture and the text "Kilroy was here" on the walls and other places where they were stationed, encamped, or visited.

An ad in Life magazine noted that WWII-era servicemen were fond of claiming that "whatever beach-head they stormed, they always found notices chalked up ahead of them, that 'Kilroy was here'".

[4] Brewer's Dictionary of Phrase and Fable notes that it was particularly associated with the Air Transport Command, at least when observed in the United Kingdom.

[2][10] War photographer Robert Capa noted a use of the phrase at Bastogne during the Battle of the Bulge in December 1944: "On the black, charred walls of an abandoned barn, scrawled in white chalk, was the legend of Gen. Anthony McAuliffe's soldiers: KILROY WAS STUCK HERE.

[6] James Kilroy had served on the Boston City Council and represented the Roxbury district in the Massachusetts Legislature during the 1930s.

[13] A New York Times article noted that Kilroy had marked the ships as they were being built as a way to be sure that he had inspected a compartment, and the phrase would be found chalked in places that nobody could have reached for graffiti, such as inside sealed hull spaces.

Maloney continued to write the shortened phrase when he was shipped out a month later, according to the AP account, and other airmen soon picked it up.

[6][18] The figure was initially known in the United Kingdom as "Mr Chad" and would appear with the slogan "Wot, no sugar" or a similar phrase bemoaning shortages and rationing.

[21] A spokesman for the Royal Air Force Museum London suggested in 1977 that Chad was probably an adaptation of the Greek letter omega, used as the symbol for electrical resistance; his creator was probably an electrician in a ground crew.

One correspondent said that a man named Dickie Lyle was at RAF Yatesbury in 1941, and he drew a version of the diagram as a face when the instructor had left the room and wrote "Wot, no leave?"

[25] This idea was repeated in a submission to the BBC in 2005 which included a story of a 1941 radar lecturer in Gainsborough, Lincolnshire, who drew the circuit diagram with the words "WOT!

to the plaintive; one sighting was on the side of a British 1st Airborne Division glider in Operation Market Garden with the complaint "Wot, no engines?"

1 doodle", noting his appearance on a wall in the Houses of Parliament after the 1945 Labour election victory, with "Wot, no Tories?

While Kilroy enjoyed a resurgence of interest after the war due to radio shows and comic writers, the name Smoe had already disappeared by the end of 1946.

[31] Correspondents to Life magazine in 1962 also insisted that Clem, Mr. Chad or Luke the Spook was the name of the figure, and that Kilroy was unpictured.

[2][3][34] An advertisement in Billboard in November 1946 for plastic "Kilroys" also used the names Clem, Heffinger, Luke the Spook, Smoe, and Stinkie.

[35] Luke the Spook was the name of a B-29 bomber, and its nose-art resembles the doodle and is said to have been created at the Boeing factory in Seattle.

Isaac Asimov's short story "The Message" (1955) depicts a time-travelling George Kilroy from the 30th century as the writer of the graffiti.

[46] In the opening credits of the 2009 American sitcom Community, two Kilroys are drawn in blue ink on the inside of a paper fortune teller, their noses forming the L's of lead actor Joel McHale's name.