Koosalagoopagoop (Koos or Koosy for short) is a fictional creature on the animated series Dexter's Laboratory. Koos is very large (but is capable of changing to any size), and has wings, a heart on his stomach, and a rainbow-colored nose and tail. Koos also wears glasses and likes to assist Dee Dee in annoying Dexter. The voice of Koosy is done by Dom DeLuise.

Koosalagoopagoop appears in the following episodes:

  • The Koos is Loose
  • Koos a la Goop a Goop (cable guide for some reason lists this as Koos 'n Boots)
  • Jeepers, Creepers, Where is Peepers?