Henry Soskin (12 February 1930 – 23 February 2022), better known as Henry Lincoln, was a British author, television presenter, scriptwriter, and actor. He co-wrote three Doctor Who multi-part serials in the 1960s, and — starting in the 1970s — inspired three Chronicle BBC Two documentaries on the alleged mysteries surrounding the French village of Rennes-le-Château (on which he was writer and presenter) — and, from the 1980s, co-authored and authored a series of books of which The Holy Blood and the Holy Grail was the most popular, becoming the inspiration for Dan Brown's 2003 best-selling novel, The Da Vinci Code. He was the last living person to have written for Doctor Who in the 1960s.

Lincoln was born in London in 1930 and studied acting at the Royal Academy of Dramatic Art. Under his original name of Henry Soskin, he worked as both screenwriter and supporting actor. In 1964 he wrote one of the episodes of The Barnstormers (Associated-Rediffusion), as well as starring in two of the episodes. Lincoln also appeared in other television series such as The Avengers (1961, 1963), The Saint (1967), Man in a Suitcase (1968), and The Champions (1969); as well as in the 1968 film Don't Raise the Bridge, Lower the River.

He was co-writer, with Mervyn Haisman, of three Doctor Who stories starring Patrick Troughton: The Abominable Snowmen (1967), The Web of Fear (1968) and The Dominators (1968) and retained the rights to the recurring character Brigadier Lethbridge-Stewart. Prior to his death in February 2022, he was the sole-surviving writer from the 1960s era of Doctor Who, following the death of Donald Tosh in December 2019.

Lincoln wrote and presented documentaries on other subjects such as The Man in the Iron Mask (Timewatch, 1988), Nostradamus, The Curse of the Pharaohs, and The Cathars (the latter three documentaries formed the television series Mysteries shown on the BBC during the 1980s).

In 1969, while on holiday in the Cévennes, Lincoln happened to read Le Trésor Maudit de Rennes-le-Château (trans: The Accursed Treasure of Rennes-le-Château), a book by Gérard de Sède about an alleged hidden treasure. The book reproduced copies of Latin parchments that had been found by the parish priest of Rennes-le-Château, Bérenger Saunière, within a pillar inside his Romanesque church.

Inspired by what appeared to be secret codes hidden in the Latin text, Lincoln did some research about the parchments and a possible treasure, writing several books presenting his theories about the area. He presented three documentaries in the Chronicle series for BBC2: "The Lost Treasure of Jerusalem", shown in February 1972, "The Priest, the Painter and the Devil", shown in October 1974, and finally "The Shadow of the Templars", shown in November 1979.^{[unreliable source?]}

One of the parchments (which was later shown to be a forgery, since the writing was written in modern French and not in 18th or 19th century French) involved a series of raised letters throughout its Latin text, spelling out a message: À Dagobert II Roi et à Sion est ce trésor et il est là mort (trans: "This treasure belongs to King Dagobert II and to Sion, and he is there dead"; or, "This treasure belongs to King Dagobert II and to Sion, and it is death").

This referred to the Merovingian king Dagobert II, who had been assassinated without a direct heir in the 7th century, thereby ending his branch of the dynasty. Later research, however, showed that de Sède's book had actually been written at the instigation of Pierre Plantard as part of an elaborate hoax to promote a society known as the Priory of Sion, and Plantard claimed to be descended from Dagobert II. Pierre Plantard died in 2000.