Jim Thirlwell (aka J. G. Thirlwell and Clint Ruin) is the mastermind behind Foetus. Most of his recent recordings have been released simply under the name "Foetus," but he has also used such band names as:

• You've Got Foetus on Your Breath
• The Foetus All Nude Review
• Foetus Eruptus
• Foetus Under Glass
• Scraping Foetus Off the Wheel
• Foetus Interruptus
• Foetus in Excelsis Corruptus Deluxe
• Foetus Inc.
• The Foetus Symphony Orchestra
• Manorexia

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