Collinder 135, known sometimes as the Pi Puppis Cluster, is an open cluster in Puppis constellation.
It consists of four stars visible also to naked eye, and a widespread population of stars. It lies in the southern celestial hemisphere near a rich star field. The main component is the star Pi Puppis, which gives to the cluster its common name; it is an orange supergiant with a visual magnitude of 2.71. The 5th magnitude stars are all variables: one (NV Puppis) is a Gamma Cassiopeiae variable, and the other (NW Puppis) is a Beta Cephei variable.