Jenner

Placeholder in the first film
In Pooh's Adventures of the Secret of NIMH, Jenner, a corrupt council member of the rats, plotted to kill Nicodemus, take the red ruby for himself, and force the other rats to stay in the rosebush and never go on to Thorn Valley. To do this, he called Giovanni to send over Team Rocket to aid his evil scheme. Although he managed to kill Nicodemus, Jenner was killed by Sullivan by having a knife thrown to his back!

Role in the second film and rest of the series
In [Pooh's Adventures of the Secret of NIMH 2]], Jenner's evil spirit refused to be killed off so easily and ordered Dr. Valentine to electroshock Martin into becoming his new body. After possessing Martin, Jenner plotted to take revenge on Justin and the Pooh gang by taking over Thorn Valley with an army of super rats and crow heartless. Eventually, Timothy managed to defeat Jenner by electroshocking Martin again, and then have Slimer and Mewtwo ghostbust the rat, trapping him forever in a ghost-trap.