The greater pipefish (Syngnathus acus) is a pipefish of the family Syngnathidae. It is a seawater fish and the type species of the genus Syngnathus.

Syngnathus acus is widely distributed along the south and west coasts of England extending up the west coast of Scotland. Recorded from several sites on the north east and south coasts of Ireland. Can be found widely distributed in north west Europe. Found in shallow waters among seaweed or rockpools and to depths of about 90 m.