The P-800 Oniks, marketed in export as the Yakhont, is a Soviet / Russian supersonic anti-ship cruise missile developed by NPO Mashinostroyeniya as a ramjet version of P-80 Zubr. Its GRAU designation is 3M55, the air launched Kh-61 variant was planned but never built. The missile has the NATO codename SS-N-26 "Strobile". Development commenced in 1983, and in the 1990s the anti-ship missile was tested on the Project 1234.7 ship. In 2002 the missile passed the whole range of trials and was commissioned. It is reportedly a replacement for the P-270 Moskit, and possibly also of the P-700 Granit.

An anti-ship missile is a guided missile that is designed for use against ships and large boats. Most anti-ship missiles are of the sea-skimming variety, and many use a combination of inertial guidance and active radar homing. A large number of other anti-ship missiles use infrared homing to follow the heat that is emitted by a ship; it is also possible for anti-ship missiles to be guided by radio command all the way.