Milo Thatch (grandson) Augustus Avery Thatch (son, deceased) Lucille Rose Thatch (Daugther-in-law, deceased)
None (Movie) John Aylward (games)
Thaddeus Thatch is the late paternal grandfather of Milo Thatch and raised him after Milo's parents died. He is the one who found the Shepherd's journal for a bet from Preston Whitmore.
Atlantis: The Lost Empire
He was more like a father to me. My parents died when I was young, he took me in
It is know that Thaddeus has been friend with Whitmore for a long time and when Whitmore got fed up about Atlantis existing, they enter into a bet where if Thaddeus finds the Shepherd's Journal, Whitmore will fund the expedition and even kiss him full on the mouth. In 1911, Whitmore funds the expedition that finds the book in Iceland and when he came back it became an embarrassment of the two. But shortly afterward, Thaddeus passes away. According to Whitmore, like Milo the board members made fun of him. But it is known that he was a friend of Joshua Sweet and told him a phrase 'when you've hit the bottom, the only place left to go is up.',
He also appeared as a cameo in trial by fire computer game and he was voiced by john aylward in the computer game.