Species 5973 was the Borg designation for multispectrum particle lifeforms encountered by the Collective in Galactic Cluster 8.

When being told by Neelix of the USS Voyager's encounter with an unknown, gaseous lifeform in 2376, Azan guessed that it was a member of Species 5973, although this was denied by Neelix. (VOY: "The Haunting of Deck Twelve")

This species was only mentioned in dialogue.