Who was Kilroy? Despite the ubiquity of the slogan "Kilroy was here" — it was common enough during World War II to have served as the title of a period humor collection, not to mention a Styx album — there’s debate over the phrase’s origin. In 1946, the New York Times (or a radio program, or both, depending on the account) declared Massachusetts shipyard inspector James J. Kilroy to be the Kilroy, but the phrase may predate the war; Chad, the little peering face who often appears with the phrase, may have been a British contribution. Chad tended to appear with a three word question, often related to rationing ("Wot, no bread?"; "Wot, no petrol?") and seems to have first been drawn by a British cartoonist, George Chatterton. Kilroy was briefly topical (Isaac Asimov wrote a pointless Kilroy story) and never quiet forgotten (more for Chad and the opportunities for visual puns than anything else). But unlike the smiley face (invented by Harvey Ball), Kilroy’s creator may never be fully known; he belongs to all of history. In ancient times, slaves marked the pyramids with graffiti. Lord Byron carved his name into a pillar in the dungeon of Chillon in Switzerland. The impulse is the same; graffiti is a way of saying, "I was here." Some graffiti is art (link via Joanne), some commemorates specific occasions (like the discovery of the Hamiltonians, the defining equation of which is carved into the Brougham bridge), and some of it is designed to mark territory, but most of it is really just tagging. Whoever started writing "Kilroy was here" was presumably named Kilroy; it’s a real, if uncommon, name. But as it progressed, it became a way to say, "Americans were here", and then just a symbol without any real meaning — an empty signifier. Some tags, by sheer ubiquity, lose their meaning; others are meaningless from the start. My grandfather, serving in the Army Air Corps over in Europe, may well have participated in a collosal piece of modern art without even knowing it. If some conceptual artist had proposed chalking "Kilroy Was Here" all over three continents, would it have been thought-provoking? Instead, it jes’ grew, saving us the tedium of serious debate about it’s meaning and making it no more or less stupid than other, more modern, means of transmitting nonsense phrases that inexplicably take root then disappear.