Robert F. Fox (born October 11, 1991), known professionally as Toby Fox, and previously as Toby "Radiation" Fox, is an American video game developer and video game composer. He is known for developing the roleplaying video games Undertale, and Deltarune, for which the former garnered acclaim and he received nominations for a British Academy Game Award and three Game Awards.
Fox's early work consisted primarily of composing music, notably doing so for the webcomic Homestuck, and following the success of Undertale, he went on to compose music for a number of other independent video games. Other more notable works include contributing to the soundtracks of Pokémon Sword and Shield and Super Smash Bros. Ultimate.