The Sikorsky Model S-58 is a helicopter originally designed for the US Navy for service in the ASW role. It was developed from the H-19 Chickasaw.

The aircraft first flew on March 8, 1954.

Initially known as HSS Seabat by the Navy and HUS Seahorse by the Marines, in 1962 all services adopted the Army designation, H-34 Choctaw.

It was also built under license in Britain by Westland as the Wessex.

US production ceased in 1970 with 1,800 built.