"I'm not scared of nothin'! I'm not afraid of the dark! I'm not afraid of Dragon! I'm not even afraid of... of the Great Owl!" Martin Brisby's quote.
The Brisby family consists of four children. Teresa, Martin, Timothy and Cynthia.
Teresa - Alledgedly the oldest and the most mature, she is seen wearing a purple dress with a pinkish ribbon on her head. She is presumed to be the oldest of the four.
Martin - The presumed second oldest and most flamboyant. Tending to cause arguments with Auntie Shrew in one scene and claiming he is not afraid of Dragon or the Great Owl. However, Martin has a soft side and apologizes to his mother for the trouble but returns to show small hatred for Auntie Shrew in the final moments of the movie. Additionally, Martin is very caring towards his siblings. This is shown when he is trying to protect his sisters from the mud whilst the house is sinking.
Cynthia - The youngest and the third female of the Brisby family, she is sweet and innocent. Although not greatly developed as a character, Cynthia makes two appearances in the Secret of NIMH.
Timothy - Timothy is the second youngest beside Cynthia, he is also the protagonist of the sequel: The Secret of NIMH: Timmy to The Rescue.
Mrs. Brisby - The head of the family and widow of Jonathan Brisby, Mrs. Brisby constantly places her children's safety before her own. In other words, she would willingly give her life as long as it meant that they would be safe. This is proven when she tries to pull the house from the mud even though there is not a chance. Another example is where Mrs. Brisby disables the tractor pulling the plow, she knows that it can cost her life but nevertheless succeeds.
*note* I have placed Mrs. Brisby on the list because instead of just mentioning the children I have mentioned the whole family.