Sam Llewellyn was born on Tresco, Isles of Scilly, where his ancestors lived for many years. He grew up in Norfolk. Llewellyn went on to live in Toronto, Canada, and Ireland, before settling in Herefordshire, England, where he still lives now. Llewellyn has a deep love for the sea, and this has influenced much of his writing. He goes sailing regularly.

He was originally an editor and fine art dealer before becoming an author. He has become a prolific writer, and has written for both children and adults. He has also worked as a journalist with newspapers and magazines from both America and Britain.

Llewellyn is married to Canadian children's author Karen Wallace. They have two sons.

Novels for adults

• Hell Bay, Arch, 1984, ISBN 0947618007
• Great Circle, Weidenfeld & Nicolson, 1987, ISBN 0297791672
• The Shadow in the Sands, 1998, ISBN 0747260052
• The Sea Garden, 1999, ISBN 0747260060
• The Iron Hotel, 2000, ISBN 0755100093
• The Malpas Legacy, 2001, ISBN 074727276X

Sailing thrillers

• Dead Reckoning, 1987
• Blood Orange, 1988
• Death Roll, 1989
• Dead Eye, 1990
• Bloodknot, 1991
• Riptide, 1992
• Clawhammer, 1993
• Maelstrom, 1994

For children

• The Well Between The Worlds, Scholastic 2009

Darlings Series

• Little Darling, Puffin, 2004, ISBN 0141316918
• Bad, Bad Darlings, Puffin Books, 2005, ISBN 0141317019
• Desperado Darlings, Puffin Books, 2006, ISBN 014131981X

Death Eric

• The Return of Death Eric, Puffin, 2005, ISBN 0141318538
• The Haunting of Death Eric, Puffin Books, 2006, ISBN 0141319844

Others

• The Magic Boathouse, Walker Books Ltd, 1994, ISBN 0744524733
• The Rope School, Walker Books Ltd, 1995, ISBN 0744536634
• Pig in the Middle, Walker Books Ltd, 1996, ISBN 0744552176
• The Polecat Cafe, Walker Books Ltd, 1998, ISBN 0744541573
• Nelson - the sailor who dared to win, Short Books, 2004, ISBN 1904095658
• Pegleg, ISBN 0755100115
• Wonderdog