Foetus is the general name for the most well-known works of J.G. Thirlwell (also known as Clint Ruin and Manorexia) that are commonly described as industrial. There have been many variations on the name over Foetus' 14 albums; the first album Deaf surfaced in 1981 under the name You've Got Foetus On Your Breath. Since the mid-90s, "main-project" releases (as opposed to projects like Manorexia) have simply used the name Foetus.

Other variations on the Foetus name include:
The Foetus All-Nude Revue
Foetus Eruptus
Foetus Uber Frisco / Foetus Over Frisco
Foetus Under Glass
Phillip And His Foetus Vibrations
Scraping Foetus Off the Wheel
Foetus Corruptus
Foetus Interruptus
Foetus in Excelsis Corruptus Deluxe
Foetus Inc.
and The Foetus Symphony Orchestra

Frenetically creative, and playing only by his own rules, Thirlwell has never stopped experimenting and evolving his sound. While his music is most often outside of any genre, it can usually best be described as Industrial or No-Wave. His music is usually quite harsh and distorted, with the notable exception of parts of the album Love, which is, in many ways, radically different from anything he has done before, using harpsichord, and what sometimes sounds like a full orchestra, but is actually only J.G Thirlwell himself (with a few guest musicians on select tracks).

He has inspired many industrial artists; like Nine Inch Nails, Pig and Cop Shoot Cop, among others, with his sonic assault and innovative use of studio technology, and was a key contributor on Coil's groundbreaking debut album Scatology.

Thirlwell has also worked on collaborations under the names of Steroid Maximus (multiple collaborators), Stinkfist (with Lydia Lunch), Flesh Volcano (with Marc Almond), Baby Zizanie (with Jim Coleman) and Wiseblood (with Roli Mosimann of Swans); and does remix work as well, often under the name of Foetus.