Brian Williams

Brian Williams was the father of Rory Williams, paternal grandfather of River Song (nèe Melody Pond), father-in-law of Amy Pond, and grandfather-in-law of the Doctor by way of the latter's marriage to River. Accordingly, he was the step-great-grandfather of Jenny and the step-great-great-grandfather of Susan Foreman.

Biography
Another man, originally presumed to have been Rory's father, sat at the head table at Amy and Rory's wedding reception at the conclusion of The Big Bang; a woman presumed to be Rory's mother sat between Rory and the man. The Doctor attended the reception, materialising the TARDIS in the middle of the assembled guests. (DW: The Big Bang)

Brian and the rest of Amy's and Rory's families and friends were under the belief that the couple honeymooned in Thailand, (DW: Dinosaurs on a Spaceship) when in fact they travelled through space and time aboard both the TARDIS (DW: The Big Bang, DW: A Good Man Goes to War) and an interstellar cruise ship. (DW: A Christmas Carol)

Brian first met the Eleventh Doctor when the TARDIS materialised around him while he was attempting to help Rory and Amy change a ceiling light bulb at their house. The Doctor had taken Rory and Amy along with Queen Nefertiti and John Riddell to investigate a ship that was headed straight to Earth and would reach it in six hours. Upon entering, they immediately found it contained dinosaurs. The Doctor did not realise that he had materialised around Brian and taken the latter aboard until after the TARDIS landed on the spaceship.

While looking at the main engines of the ship, the Doctor, Rory and Brian were taken to Solomon by his robots. Solomon had killed all the Silurians on this Silurian Ark and forced the Doctor to repair his legs so he could make off with the cargo. Discovering he had a few hours until the ISA launched missiles at the ship and unable to pilot the ark, Solomon took the most valuable thing on the ship identified by his IV system, Nefertiti. The Doctor magnetised the ark, trapping Solomon's ship that was inside. The Doctor released it once he put the signal of Silurian Ark inside Solomon's ship. The ISA missiles destroyed Solomon. Rory and Brian, who possessed the same gene chain, were able to pilot the ark to safety with the parallel pilot compartments. The Doctor returned everyone home, and gave Brian a sense of adventure when he saw the Earth from space. Brian began travelling around the world and sending homemade postcards back to his son and daughter-in-law. Among the postcards was one from the planet Siluria to which he accompanied the Doctor and the dinosaurs aboard the Silurian ark. (DW: Dinosaurs on a Spaceship)