Mungojerrie seems to have been somewhat neglected by many fans, as opposed to his widely loved counterpart Rumpleteazer. This is puzzling.
It is said, in the poem and song "Macavity: The Mystery Cat," that Macavity commands a gang of criminal cats including Griddlebone and Mungojerrie. In the original poem, Rumpleteazer is mentioned as well. However, Mungojerrie and Rumpleteazer do not side with Macavity during the cat fight, and in fact fight against him, leading to the theory that perhaps they had a past with Macavity but are now part of the Jellicle tribe and on the side of the junkyard cats.
The nature of the relationship between Mungojerrie and Rumpleteazer is unknown, and seems to vary between productions. Due to the similarity of their markings, however, many believe them to be siblings or twins. Others believe that they are mates, and a few people even say that they are both. I believe that, along with Mistoffelees and Rum Tum Tugger, this is one of the most debated relationships in the Cats fandom.
Mungojerrie is portrayed by Drew Varley in the 1998 film.