In the mirror universe, Elba II was a planet under the control of the Terran Empire during the mid 23rd century.

In 2269, a gathering of Imperial Starfleet personnel took place on Elba II to acknowledge and celebrate the recent promotion of Captain Spock to the rank of Admiral. In attendance was Grand Admiral Garth of Izar and his wife Marta, an Orion.

Garth's intention was to use his ability to shape-shift and disguise himself as Spock; he would then have himself beamed up to the ISS Enterprise (NCC-1701) where he believed Spock had some ultimate weapon hidden in his quarters. Unknownst to Garth, Spock had learned of his shape-shifting abilities from Captain James T. Kirk's log entries and had prepared for any subterfuge on Garth's part.

Garth and his wife were subsequently disintegrated by Marlena Moreau who had been observing the pair through the Tantalus field. (TOS novel: The Sorrows of Empire)

It is unknown if the mirror Elba II had an asylum on its surface as in the case of the Federation-universe Elba II.