Mastigias ocellatus, the golden medusa, is a species of jellyfish in the family Mastigiidae. It is native to the southern Pacific Ocean.

Etymology The specific epithet is derived from the Latin ocellatus, "having small eyes", referring to the white spots on the edge of the bell that appear similar to small eyes.

Description The medusa of Mastigias ocellatus grows to a diameter of about 15 cm (6 in). The surface of the bell is sculptured with small, polygonal nematocyst warts. There are 96 marginal lappets and eight three-winged mouth arms, terminating in a bare, club-shaped extremity, the tip of which is blue. The bell is reddish-brown, with white spots near the edge, each with a brown centre and margin.

Distribution Mastigias ocellatus occurs in October in the southern Pacific Ocean. It is a pelagic species, and its method of reproduction has not been studied.