Thengel

Thengel was the sixteenth king of Rohan, the father of Théoden and Théodwyn and the grandfather of Théodred, Éomer, and Éowyn.

History
Thengel married Morwen Steelsheen and had four children with her: three daughters (one of them named Théodwyn) and one son, Théoden.

Friendship with Aragorn
Aragorn and Thengel once rode out together.

Later Life
Aragorn left Thengel's survice. Thengel eventually died and his title passed onto Theoden.