Born James Paul Czajkowski and known by his pen names James Rollins and James Clemens, he is a novelist renowned for his fantasy and action adventure series' including the Sigma Force series and the Sanguines trilogy.
He worked successfully as a veterinarian in Sacramento, California, before closing his practice to be a full-time author.
He published his first novel Wit'ch Fire and a number of other fantasy novels under his original pen name James Clemens.
He was born in Chicago, Illinois but later lived in California. He grew up as one child of seven.