El-Adrel IV was a planet in the El-Adrel system.

Until the 24th century, it was considered uninhabited; an incident with a powerful "entity" on the planet proved this to be otherwise. The creature in question was fought by Starfleet Captain Jean-Luc Picard and Children of Tama Captain Dathon. (TNG episode: "Darmok")

In 2393, the Tamarians jointed the United Federation of Planets. The same year, a "linguistic research facility" was opened on El-Adrel IV, jointly run by the Tamarians and Starfleet. The facility was run by Meltha who indicated said facility was due to the work of Dathon and Picard. (ST website: The Path to 2409)