Justin - or sometimes known as Captain Justin, Justin the Rat, Prince Justin, or The Captain of the Guard - is One of the rats who escaped from NIMH.
Justin is Friends with Jonathan Brisby. Justin is introduced to Mrs. Brisby and Mr Ages as they set off to find Nicodemus for help. Justin fell in Love with Mrs. Brisby since they first met.
Following the death of Nicodemus - Justin took over as the Leader of the rats. Then - he teams up with Jeremy the Crow to save the Hundred Acre Wood.
In a segment The Cave of Wonders - Justin is remarried to Mrs. Brisby.
He is voiced by Peter Strauss in the original film and Doug Erholtz in the spin offs.
His is voiced by Jeff Glen Bennett in The Mrs. Brisby and Fievel Show