USS Observer (AM-461/MSO-461) was an Aggressive-class minesweeper acquired by the U.S. Navy for the task of removing mines that had been placed in the water to prevent the safe passage of ships. The second ship to be named Observer by the Navy was laid down 20 July 1953 as AM-461 by Higgins, Inc., New Orleans, Louisiana; launched 19 October 1954 sponsored by Mrs. E. V. Richards, reclassified MSO-461 on 2 February 1955, commissioned 31 August 1955, Lt. Comdr. P. H. Barkley in command.