Old Dinny was a male mole resident of Moledeep who was the grandfather of Young Dinny, the great-great Grandfather of Togget, and a good friend of the Foremole in Mossflower. He was known to be the most skilled and powerful mole at his time, even though he appears as being quite old.
As a youth, he was friends with Boar the Fighter. While investigating the temporarily abandoned fortress of Kotir, Old Dinny discovered the underground lake where the Gloomer was once kept and a secret passage leading into Mossflower Woods, a discovery that would lead to Kotir's eventual flooding.