Mason Fairbanks (voiced by Michael York) is a treasure hunter who is 66 years old.
When the test reveals Fairbanks to be Homer's father they celebrate with a treasure hunt, which goes wrong when the submarine Homer is in gets trapped between rocks underwater.
In his final moments, Homer reminisces about the many things Abraham had done for him growing up, only to be rescued by Fairbanks then have Abraham admit to having switched DNA samples during the paternity test, wanting to preserve the happiness Homer had been feeling with Fairbanks.
He appeared at Mona's funeral.
When Homer auctions off a painting he brought from the Van Houtens, Mason is one of the bidders.