Topau

Topau was the builder of the temple that held the body of the Aztec Yetaxa. He was the father of Ixta. He had been in love with Cameca, but disappeared, taking the knowledge of the entrance to the temple's tomb with him. When Cameca stated that he watched over the temple every day, the First Doctor assumed that he was a gardener. (TV: The Aztecs)

Behind the scenes
In the novelisation, he is Ixta's grandfather.