Achernar II (also known as "Alpha Eridani II") was a world in the capital system of the Imperial Romulan State.

In 2156, the entity known as Redjac murdered several females in this planet's city Heliopolis. (TOS episode: "Wolf in the Fold"; ENT novel: Beneath the Raptor's Wing) Until December of 2379, it was a planet in the Romulan Star Empire. That month, the planet fell under the control of the newly-formed Imperial Romulan State. (ST novel: Articles of the Federation)