The Hooloovoo is a super-intelligent shade of the color blue. A Hooloovoo participated in the construction of the starship Heart of Gold. He was temporarily refracted into a free-standing prism for the ship's launching ceremony.
- In the Doctor Who episode "The Rings of Akhaten", the Doctor lists a Hooloovoo as one of the aliens he recognizes on the streets of the titular rings. The Hooloovoo appears as a masked humanoid figure, indicating that it might not be the same species from The Hitchhiker's Guide to the Galaxy, although it could also represent a Hooloovoo housed in an artificial humanoid body.