USS PC-815 was a PC-461-class submarine chaser built for the United States Navy during World War II. Its first commander, for about eighty days in 1943, was L. Ron Hubbard, who later became the founder of Scientology. After Hubbard was removed from command for conducting unauthorized gunnery practice in Mexican territorial waters, the PC-815 served as a shore patrol vessel off San Diego, California.

The PC-461-class submarine chasers were a class of 343 submarine chasers constructed mainly for the US Navy and built from 1941 to 1944. The PC-461s were based primarily on two experimental submarine chasers, PC-451 and PC-452. While PC-461 began the series, the first of the class to enter service was PC-471. As part of the Lend-Lease program, 46 ships of this class were transferred to allies of the United States. Fifty-nine PC-461s were converted to other types of patrol vessels. Eight vessels of this class were lost, and one vessel was lost after conversion to a PGM-9-class motor gunboat. Only one of the class, USS PC-566 commanded by Lieutenant Commander Herbert G. Claudius, actually sank a submarine, U-166, during World War II; however, the website 'Patrol Craft Sailors Association' cites PC-461-class ships sinking or assisting sinking up to 6 German and Japanese subs.