Additional voice credits go to the following:
- Nicodemus, the old wizard who was the leader of the NIMH Rats was voiced by Derek Jacobi, an actor who has done occasional voice work for other animated films. He also has the distinction of portraying Archibald Craven in both the 1987 made for TV movie, The Secret Garden, and the voice of the same character in the 1994 animated TV movie of the same name. In the 2000 film Gladiator his character, Gracchus, spoke thusly, "I don't pretend to be a man of the people. But I do try to be a man for the people."
- Elizabeth Hartman voiced the kindly Mrs. Brisby. Although she had a short career that ended with a suicide in 1987 she was featured in several films that have made their way into the American lexicon. She starred opposite Joe Don Baker and Leif Garrett in Walking Tall. She flirted with Clint Eastwood in The Beguiled. And she put up with Alan Arkin and Ed McMahon in Full Moon High.
- Mr. Ages, the old tinkering mouse, was voiced by Arthur Malet, who has a large body of work as a voice actor, but forayed into live film as well. You probably remember him as Tootles from Hook, or as Hinton from The Scorpio Letters, or maybe you saw him portray Wendel in Beastmaster 2: Through the Portal of Time.
- Surely everyone recognized Dom DeLuise as the Crow Jeremy? His body of work is enourmous and influential, from The Cannonball Run, to Baby Geniuses. In a strange but unrelated coincidence he did the voice of Nicodemus in Timmy’s Gift: Precious Moments Christmas.
- Hermoine Baddeley voiced Auntie Shrew and had several Disney credits under her wing. She was Madame Adelaide Bonfamille in the Aristocats and Mrs. Flower in C.H.O.M.P.S. Sadly she passed away of a stroke in 1986, she was 80 years old.
- Shannen Doherty played the eldest daughter, Teresa, but that's been covered already.
- The Eldest boy, Martin, was played by Wil Wheaton, you'll remember him as the whiny one from Star Trek: The Next Generation, and the presumably young Stephen King character, named Gordie in Stand By Me, who spoke the immortal words, "Suck my fat one you cheap dime store hood."
- Ian Fried played little sick Timmy. He didn't actually do a whole lot of acting, but you probably remember him as Rocky Junior in Rocky III.
- The Great Owl was performed by none other than the venerable John Carradine. Carradine was a magnificent Shakespearean actor and worked virtually his entire life. On film he played everyone from Moses's brother Aaron in The Ten Commandments to the killer, Gaston Morrel in Bluebeard. He was also the father of Kwai Chang Caine.
- Peter Strauss voiced Justin, the kindly rat who championed Mrs.Brisby. He has a laundry list of TV Movies and was Wolff in Spacehunter: Adventures in the Forbidden Zone. He also named his son Justin after his charachter in the Secret of NIMH.
- Paul Shenar was Jenner, the machiavellian upstart rat who killed Nicodemus. He also played John Carrington in Roots, Rocca in Raw Deal and Alejandro Sosa in Scarface.
- Tom Hatten was Farmer Fitzgibbons, the ruffled man who let NIMH bulldoze his rose bush. You may remember him as General Miegs in Spies Like Us.
- The sweet voice of Mrs. Fitzgibbons was Lucille Bliss best known as the voice of Smurfette, Anastasia in Disney's Cinderella and Mrs. Bitters in Invader ZIM.