Kilroy Was Here is arguably the world's first viral meme, originating during World War II. It features a simple line drawing of a man with a large nose peeking over a wall, accompanied by the signature phrase. It was popularized by American GIs who would scrawl the image on walls and equipment in every theater of the war to signal their presence. While its exact origins are debated—often linked to a shipyard inspector named James J. Kilroy—the symbol evolved into a powerful mark of solidarity and omnipresence. Today, it stands as a precursor to modern internet culture, representing the universal human urge to leave a mark and signify existence in a specific time and place.