Philip Carrigan Johnson Jr. was a United States Navy officer. He served during the Mexican–American War and commanded two ships in combat during the American Civil War. After the war, he commanded the coastal survey ship Hassler from 1871 to 1872 during an expedition to the Strait of Magellan and both southern coasts of South America accompanied by natural historian Louis Agassiz.

The schooner Hassler was the first iron-hulled steamship used in the service of the United States Coast Survey.