Tom R. Buchanan (born October 30, 1955) was a player on the reality show Survivor. He was best known on the show by the nickname "Big Tom".

Buchanan was born in Rich Valley, Virginia and still resides there. He and his family have farmed in the area for three generations. Buchanan attended Tennessee State University. He is a member of the Virginia Cattleman's Association, the Rich Valley Farmer's Club and the Rich Valley Presbyterian Church. Since appearing on Survivor, Buchanan has acted as a spokesman for literacy education. Buchanan has a wife, Sandy, and a son, Bucky Bo.

Tom was assigned to the Boran tribe in the Survivor: Africa series in 2002. He formed an alliance with tribemates Lex van den Berghe and Ethan Zohn. On the fifteenth day of the show, Tom was one of three players (along with Lex and Kelly Goldsmith ) who were reassigned to the rival Samburu tribe (this was the first time on the show that players were moved between tribes). The players however retained their loyalty to their original tribemates rather than form new alliances and when the new Samburu tribe lost its first immunity challenge, the voting was split between the original and the new members. The three original Samburus voted against Tom and the three former Borans voted against Lindsey Richter (who lost the tie because of former votes against her). When the tribes merged, the alliance of Tom, Ethan, and Lex remained firm and the other players were voted off one by one. However on the 39th day, when the three allies and Kim Johnson were the four remaining players, Kim won her first immunity and Tom was voted out. Kim won a second and final immunity challenge and chose Ethan as her competitor in the final council. Tom stayed with his longtime alliance and voted for Ethan, who won the million dollars in a 5-2 vote.

After the series was completed it was learned that the producers had made an error in awarding Kim the victory over Tom. The challenge was a trivia contest with questions about the other players. The deciding question was which female player did not have any piercings. Tom answered Lindsey, which the producers thought was an incorrect answer. Kim answered Kelly, which the producers regarded as the only correct answer, and was awarded the immunity. However, it was later revealed that Lindsey Richter did in fact not have any piercings and both players had been correct. CBS acknowledged the error and gave Tom and Lex the $100,000 they would have received if they had gone on to win second place in the series.

In 2004, Tom returned to compete in the Survivor: All-Stars series. In this series, Tom began in the Chapera tribe. Tom joined the existing alliance of Rob Mariano and Amber Brkich. With Rob leading the alliance, Tom was able to play a quiet game and avoid making enemies. (One tribemate Tom did not get along with was Sue Hawk and after she quit the game, Tom celebrated by dancing and singing Ding Dong The Witch Is Dead.) However after a tribal shuffle brought Rupert Boneham and Jenna Lewis into the tribe, Rob and Amber also formed an alliance with them. After the five players had voted off all of the other competitors, Rob's worries that Tom might betray him caused him to decide to favor his alliance with Rupert and Jenna over his original alliance with Tom. Tom was voted off by the other four on the 34th day. Tom, angry over Rob's betrayal, voted for Amber in the final vote against Rob, which she won in a 4-3 vote.

Overall, Buchanan's strategy was to present himself as a simple country boy and occasionally act like a clown, knowing this would cause many other players to underestimate him as a threat. He also organized strong alliances and remained loyal to them. Buchanan's abilities in the game kept him in competition for a combined total of 73 days; the most ever for any Survivor player.