Ovus was an extremely old, gluttonous tawny owl, and a good friend of Bluddbeak, an ancient red kite. He appeared when the creatures of Redwall Abbey were being frightened by the three adders, Zassaliss, Harssacss, and Sesstra. After hearing about the danger of the snakes, Ovus doggedly flapped off to the Northern Mountains to find Bluddbeak, who, in his younger days, had been famed for being an adder killer.
The tawny owl brought the red kite back to Redwall Abbey, then, against the wishes of several abbeybeasts, the two birds went off to hunt for the snakes. However, even Bluddbeak could do nothing about Zassaliss, Harssacss, and Sesstra, for his age had severely diminished his power. Both he and Ovus were slain by the snakes, and the kite's body was carried off by the adders, but the body of Ovus was buried in Mossflower Woods by the Redwallers.
It is highly likely that Ovus' name is based off of ovum, the Latin prefix which denotes anything to do with eggs.