USS Portunus (AGP-4) was an LST-1-class tank landing ship acquired by the United States Navy for use during World War II as a motor torpedo boat (MTB) tender.

After shakedown along the East Coast of the United States, this motor torpedo boat tender departed the U.S. 23 July 1943 in task group TG 29.6 for the Panama Canal, whence she continued to Australia.

Through December, she underwent overhaul at Brisbane, Australia, and on 29 January 1945 returned to Mios Woendi and resumed repair work.

On 16 April she joined company with the remainder of TG 78.2 to land the 24th Infantry Division, United States Army and secure Parang, Mindanao.

Portunus earned 3 battle stars for World War II service This article incorporates text from the public domain Dictionary of American Naval Fighting Ships.