Longcat, originally known as Shiroi (Whitey), became an internet sensation in the mid-2000s after appearing on the Japanese imageboard 2chan. The meme features a white cat being held up, appearing impossibly long, which led to the iconic catchphrase 'Longcat is long.' It eventually evolved into elaborate digital lore involving an epic cosmic battle between Longcat and its dark counterpart, Tacgnol. As one of the earliest and most recognizable 'macro' cat memes, it helped define the early era of internet humor, symbolizing the joy of Photoshop edits and the birth of feline-centric web culture.