C. J. Sansom is an English writer of crime novels.

He came to prominence with his series set in the reign of Henry VIII in the 16th century, whose main character is the hunchbacked lawyer Matthew Shardlake. Shardlake works on commission initially from Thomas Cromwell in Dissolution and Dark Fire and then Thomas Cranmer in Sovereign.

He has also written Winter in Madrid, a spy thriller set in Spain in 1940.

Sansom was educated at the University of Birmingham, where he took a BA and then a PhD in history. After working in a variety of jobs, he decided to retrain as a solicitor. He practised for a while in Sussex as a lawyer for the disadvantaged, then he quit in order to work full-time as a writer.

Dark Fire won the 2005 Ellis Peters Historical Dagger, awarded by the Crime Writers' Association (CWA). Sansom himself was "Very Highly Commended" in the 2007 CWA Dagger in the Library award, for the Shardlake series.

The BBC have commissioned an adaptation of Dissolution with the actor Kenneth Branagh set to star as Shardlake. The rest of the Shardlake books are expected to follow. C. J. Sansom has been consulted on the series, which is in the final stages of negotiation.

Winter in Madrid is a spy novel written by C. J. Sansom. The setting is just after the Spanish Civil War in 1940 and London, England. The main character is a wounded veteran, Harry Brett. He received his wounds during the Dunkirk withdrawal.