The Viruses, also known as the Sparks, are minor antagonists from The Brave Little Toaster to the Rescue.
Role in the film
They appear during the "Chomp and Munch" sequence as they plague Wittgenstein by destroying his inner tubes and circuitry while singing the chorus part of the song. When Wittgenstein is later revived by Radio's WFC 11-12-55 tube, the viruses automatically get destroyed (though a few remaining ones form the word "Yipe!" before they too are destroyed) and are never seen again throughout the rest of the movie.