Robert Todd Lincoln Beckwith (July 19, 1904 – December 24, 1985) was an American gentleman farmer known as a great-grandson of Abraham Lincoln. In 1975, he became the last undisputed descendant of Lincoln when his sister, Mary Lincoln Beckwith, died without children. Though Timothy Lincoln Beckwith was born to second wife Annemarie Hoffman Beckwith in the midst of divorce proceedings in 1968, Robert Beckwith contended—and the court agreed—that his paternity was highly unlikely, as he had undergone a vasectomy in the early 1960s.
Robert Todd Lincoln Beckwith was born in Riverside, Illinois, to Jessie Harlan Lincoln and Warren Wallace Beckwith. Jessie's parents were Robert Todd Lincoln—a son of Abraham Lincoln—and Mary Eunice Harlan. Jessie eloped in 1897 with Warren Beckwith, a classmate and football star at Iowa Wesleyan College. Before their divorce in 1907, they had two children: Mary Lincoln Beckwith, who died in 1975, and Robert Todd Lincoln Beckwith.
Beckwith attended a private school in Washington, D.C., and New York Military Academy in New York City, in addition to spending two years at his grandfather Robert Todd Lincoln's previous boarding school, Phillips Exeter Academy. He later received a law degree from what is now Georgetown University.
Beckwith enjoyed boating and sailing and generally avoided the media and publicity. On one occasion, a newspaper published pictures of him as a young man when he was arrested for speeding in Omaha, Nebraska.
Beckwith's mother died in 1948 and in later life, he gave his profession as "gentleman farmer of independent means", his inheritance having included a working farm in Middlesex County, Virginia.
Beckwith was a representative for Illinois Day as part of the 1964 New York World's Fair. In June 1965, he received an honorary doctorate degree from his parents' school, Iowa Wesleyan College. Also in 1965, he was a guest of honor at Chicago's commemoration ceremony upon the 100th anniversary of Lincoln's funeral.
In 1967, Beckwith was quoted as saying he "was not especially interested" in his ancestors' life in the White House. He did however retain some Lincoln memorabilia, most of which he gave to the state of Illinois, and Lincoln's rifle which he later gave to the Smithsonian Institution.
Beckwith's first marriage, in March 1927 and lasting nearly 39 years, was to Hazel Frances Holland Wilson (1899–1966), an older widow with two children including a son ten years his junior.
In November 1967, he married his second wife, Annemarie Hoffman (German-born c. 1940), who gave birth to a son in October 1968, named him Timothy Lincoln Beckwith, and listed Robert Beckwith as the boy's father. Robert Beckwith, however, was in the process of divorcing her, accusing her of adultery and denying paternity of the child since he had a vasectomy six years prior. During the divorce battle, the court ordered her to have her son undergo a blood test. She never complied with the order, and the Superior Court of the District of Columbia granted the divorce in September 1976, ruling that Robert Beckwith was not the father, though leaving any inheritance decision for another court case. After Robert Beckwith's death in 1985, three charities that stood to inherit his fortune contacted Timothy and arranged a settlement with him of over $1 million. Timothy, who has always avoided public attention and does not grant interviews, became an assistant state's attorney at the Palm Beach County State Attorney's Office in West Palm Beach, Florida.
Beckwith and his third wife, Margaret Elizabeth Hogan Fristoe (1921–2009), married in 1979; she was described in her Washington Post obituary as an Air Force wife and volunteer, in reference to a prior marriage, from which she had a daughter.