Companon Coob is an object in ITS MY LIFE!. As its Portal equivalent is well-known and has become a practical symbol of Portal, importance is placed on it in ITS MY LIFE!
It is likely that several Companon Coobs exist, as Marrissa Roberts refers to hers specifically as being "my". Therefore, stories of different Companon Coobs may differ.
Marrissa's Companon Coob has apparently been testing alongside her, as she mentions that she hasn't seen him in months. It first actually appears in chapter 5 of ITS MY LIFE!, as GLaDOS presents it to Marrissa and asks her to throw it through a portal to Andord Hell. However, Marrissa refuses, which leads GLaDOS to pumping the room Marrissa is in with neurotoxin. Unfortunately for GLaDOS, though, Marrissa is immune to neurotoxin, and thus she gets to keep her Companon Coob.
In Portal: The 4th Millennium: The Trollfic Edition, there is a brief allusion that Companon Coob is in fact the same guy as Dom Cobb from the movie Inception. Principal Business Man, during his visit to Portal Labs, has also come across a Companon Coob, but incinerates it without much thought.
- Its name has been misspelled once as "companion boob".