This is the "house name" used by Gold Eagle Books, an imprint of Harlequin Enterprises Ltd for their lines of action adventure books. Most of the works credited to the house name were in the Deathlands series or the Outlanders series.
At this time (2019) there are over 125 titles in the Deathlands series and over 75 titles in the Outlanders series.
Some of the writers who have appeared under the name James Axler include:
Jack Adrian
Laurence James
Mark Ellis
Mel Odom
Terry Collins
Nick Pollotta
Andy Boot
Alan Philipson &
Rik Hoskin