Great Owl.

the Great Owl is the owl that lives in the forest he seems monsterious but he is also very wise and good comrad to Nicodemous he is first seen in the treehole where he squishes a spider that is stalking Mrs Brisby and he advises her to seek help from rats in a rosebush with their leader Nicodemous so he flies off when night falls to go hunting he is not seen again for the rest of the film.