USS Pybus (CVE-34) was initially a United States Navy Bogue-class escort carrier. The ship was transferred to the United Kingdom for service in the Royal Navy as the Ruler-class escort carrier HMS Emperor (D98) as part of the Lend-Lease program of World War II. Entering service in 1943, the ship took part in operations against the Tirpitz and the invasions of Normandy and southern France. Returned to the United States following the war, the carrier was sold for scrap in 1946.

The Bogue class were a class of 45 escort carriers built in the United States for service with the US Navy and the Royal Navy, through the Lend-Lease program, during World War II. Following the war, ten Bogue-class ships were kept in service by the US Navy and were reclassified for helicopter and aircraft transport operations.