Barnabas T. Bullion was a member of the wealthy East-Coast Bullion mining-family during the 19th century. He became a member of the Society of Explorers and Adventurers during the period of its global expansion, lead by members Jason Chandler and Lord Henry Mystic. In 1870, Bullion went on a S.E.A. river-expedition along the Colorado River. Within the S.E.A., Barnabas became friends with Jason Chandler and went on an expedition with him to the golden city of El Dorado.
Believing gold to be his birthright, Bullion did not relent his mining efforts and in 1880 contacted Jason Chandler (now president of the Society) for assistance. Chandler being an inventor sent Bullion advanced tech for the company to use alongside advice from one Madame Zarkov from the Museum of the Weird on the mountain's spirits. Chandler and Zarkov both advised Bullion to cease his mining and leave the region but Bullion refused and eventually died at some point between 1880 and 1899.
Barnabas was created and introduced to the attraction's backstory as part of a 2013 refurbishment. He was modelled after imagineer Tony Baxter who created much of Big Thunder Mountain Railroad and Disneyland Paris' Frontierland. Behind-the-scenes it was allegedly planned for Disneyland Paris' Big Thunder to not be cannon to the story of Disneyland Paris' Big Thunder with him being a counterpart to Big Thunder Mining Company founder Henry Ravenswood. However since this there have been countless overt story connections between Disneyland Paris' Big Thunder and the American versions of the attraction, many being found in the same 2013 refurbishment. As a result, Bullion's status as supposed founder of the Big Thunder Mining Company is highly dubious.
Barnabas is only seen in the queue in portrait form though his presence is present throughout. At the Magic Kingdom, letters in the queue also identify him as a member of the Society of Explorers and Adventurers. He bought a drilling machine from fellow member Jason Chandler for his current mining operation, but in light of the recent supernatural happenings, Chandler has been advising him to stop and move onto a more stable site.
At Disneyland, his portrait can be seen in the window of the Panhandle Hotel in the town of Rainbow Ridge. During the creation of Star Wars: Galaxy's Edge, a parcel addressed to him was found in Frontierland.
Barnabas T. Bullion is a major character in the Big Thunder Mountain comic, with his daughter Abigail Bullion moving to Rainbow Ridge and getting involved in finding out just what's wrong with her father's mining operation.
Barnabas is stubborn in trying to get the mining operation to work to better support the town, but his foreman Wilikers has little regard for the safety of the miners and has generally kept him in the dark just how bad conditions have gotten in the mines.
The sympathetic interpretation of Barnabas in Disney Kingdoms was the result of talks the authors had with Tony Baxter, did not want his likeness to be used for a comic-book villain.
In the Society of Explorers and Adventurers portrait at Mystic Manor, some fans speculated that one of the men featured in the portrait was Barnabas. According to WDI Story Editor Kevin Lively, it isn't him because he died "long before 1899".