Martin Brisby is a supporting character in Don Bluth's 1982 film The Secret of NIMH and the main antagonist of the 1998 sequel The Secret of NIMH 2: Timmy to the Rescue. He is the eldest son of Mrs. Brisby and Jonathan Brisby next to Teresa Brisby who is the oldest daughter and the older brother of Timothy Brisby and Cynthia Brisby.
He was voiced by Wil Wheaton as an 8 year old in the first movie, Philip Van Dyke as a 12 year old, Eric Idle as an evil 19 year old, and Martin Phillips as a reformed 19 year old in the sequel.
The Secret of NIMH (1982)
At first, Martin Brisby is seen home alone with his siblings until Auntie Shrew arrives to inform Mrs. Brisby of Moving Day. Mrs. Brisby is not present so the shrew decides to wait. Martin provokes an argument with Auntie Shrew which prompts her to depart; Mrs. Brisby shows up and she’s told to keep Martin under control and Moving Day is at hand. Additionally, she tells Mrs. Brisby to move her "very odd family". Martin is not seen until the Shrew tells him and his siblings to look after Jeremy the Crow. And after that he is not seen until the climax of the movie where the house sinks into the mud. His last appearance is in the last moments of the film.
The Secret of NIMH 2: Timmy to the Rescue (1998)
He is the hidden main antagonist of the sequel. He was captured by NIMH. He became insane when the doctors brainwashed him. After being made insane, Martin took over the lab and brainwashed Dr. Valentine with a device similar to the one Valentine used on him and made him think he was a dog. Martin plans to use an army of lab rats riding a flock of ravens to take over Thorn Valley.
He asks Timmy to join him, but he refuses and is locked in a cage as Martin drags Jenny away to try to make her his queen. Timmy escapes with the help of Cecil and they go to free Jenny. Together, they knock out Martin and Timmy tricks Martin's army of ravens and rats to fly in the wrong direction.
Timmy and Jenny then leave to find the others, only to find once everyone is free that NIMH is on fire. The survivors (Timmy, Jenny, and her parents, as well as Justin and Brutus) flee. Timmy goes back to save Martin. Before he leaves, Jenny tells him she loves him and he tells her the same.
After being attacked by the cats Muriel and Floyd once again, Timmy sends them down an elevator shaft and finally finds Martin, actually, Martin finds him. Timmy and Martin are able to escape through the lab's skylight, with some help from Jeremy. Jeremy takes the survivors to safety. The mice return to Thorn Valley, and Martin returns to normal.