Darklands Trilogy was created in 2005.
Darklands - film - was created on 1997-11-26.
Darklands - video game - was created in 1992.
Beyond the Darklands - TV series - was created on 2009-03-18.
There is a third book, titled 'Daywards', but it's not scheduled for release by the University of Queensland Press until April 2010
The Prodigal Trilogy was created in 2008.
Viking Trilogy was created in 1957.
Auton trilogy was created in 1998.
Underworld Trilogy was created in 2010.
The Wimbledon Trilogy was created in 1993.
The Firebringer Trilogy was created in 1985.
The Magician Trilogy was created in 1986.
The Bounty Trilogy was created in 1936.