Rhundurin was a legendary dwarf mentioned by Vimme Vivaldi.
In The Witcher 2: Assassins of Kings[]
The main market square in the town of Vergen is called "Rhundurin Square".
In The Witcher 3: Wild Hunt[]
During Of Swords and Dumplings quest, the dwarf which guards van Hoorn's warehouse expresses his surprise exclaiming "by Rhundurin!", if Geralt gives him 200 crowns with regards from Yarpen Zigrin.