Collilongus (meaning "long neck") is an extinct genus of small archosauriform, possibly a rauisuchian, known from Early Triassic (Olenekian age) rocks of Czatkowice 1, Poland. It was first named by Magdalena Borsuk−Białynicka; and Andriej G. Sennikov in 2009. The type and only known species is Collilongus rarus. It is a rare component of the Czatkowice 1 fauna, known only from vertebrae. Collilongus was a contemporary of the more common archosauriform Osmolskina.