Reihairem was a city on planet Sigma Niobe II. It was, as of the mid 23rd century, a remote port of the Yemai Empire, and as such was home to a number of Niobeans from beyond the Empire.

Rehairem was the port closest to the Ilaiyen Archipelago, and was the starting point of Admiral Deyin Kaiyel-Ned's expedition to those islands in 2268. James T. Kirk and five other members of the USS Enterprise crew signed aboard Deyin's flagship, the Enai-ra, at Reihairem. (TOS short story: "As Others See Us")