The Prestonian-class ocean anti-submarine escort frigate was a class of 21 frigates that served with the Royal Canadian Navy from 1953–1967 and with the Royal Norwegian Navy from 1956–1977.

The River class was a class of 151 frigates launched between 1941 and 1944 for use as anti-submarine convoy escorts in the North Atlantic. The majority served with the Royal Navy and Royal Canadian Navy (RCN), with some serving in the other Allied navies: the Royal Australian Navy (RAN), the Free French Naval Forces, the Royal Netherlands Navy and, post-war, the South African Navy.