| Named By: | M. BorsukinBialynicka & A. G. Sennikov in 2009 |
| Time Period: | Early Triassic |
| Location: | Poland |
| Size: | Unavailable |
| Diet: | Carnivore |
| Fossil(s): | Vertebrae |
| Classification: | | Chordata | Reptilia | Diapsida | Archosauromorpha | Archosauriformes | |
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-Bialynicka; 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.