HD 17156 b, also known as Mulchatna, is a gas giant exoplanet that orbits a F-type star. Its mass is 3.51 Jupiters, it takes 21.2 days to complete one orbit of its star, and is 0.16278 AU from its star. Its discovery was announced in 2007.

Mulchatna and its star, Nushagak (HD 17156), were given names by the International Astronomical Union and suggested by the public. Both are named for rivers in Alaska known for salmon that have long supported indiginous and native populations.

The Mulchatna is a tributary of the Nushagak River, much like a planet is bound to its star. The star and planet are in the Cassiopeia constellation, 255 light-years away.