Megalovania was composed by Toby Fox and became famous as the theme for Sans's boss fight in Undertale, released in 2015. The track later reached an even wider audience when Sans joined Super Smash Bros. Ultimate as a Mii costume fighter, bringing the song into Nintendo's crossover. Online, short clips spread through gaming streams, YouTube edits and TikTok, where the melody became shorthand for an unexpected showdown. Its speed, familiarity and comic seriousness keep it a favourite for creators who want an instant boss-battle feeling.