Knaak attended the University of Illinois at Urbana-Champaign, studying rhetoric, and earned a bachelor's degree.

After reading Andre Norton's Storm over Warlock, he eventually sold his first short story in 1986, and it was published in 1987. He has listed several of his influences, and even a few of his favorite fellow authors, those being Edgar Allan Poe, Robert E. Howard, Glen Cook, L. Sprague de Camp, Lawrence Watt-Evans, Harry Turtledove, Jennifer Roberson, Laurell K. Hamilton, Harry Harrison, and Robert Sawyer.

He splits living in Illinois and Arkansas.

Dragonlance

1. Series
1. The Legend of Huma (1988), ISBN 0-88038-548-0
2. Kaz the Minotaur (1990), ISBN 0-88038-910-9
3. Land of the Minotaurs (1996), ISBN 0-7869-0472-0
4. Reavers of the Blood Sea (1999), ISBN 0-7869-1345-2
5. The Citadel (2000), ISBN 0-7869-1683-4
2. Minotaur Wars
1. Night of Blood (2003), ISBN 0-7869-2938-3
2. Tides of Blood (2004), ISBN 0-7869-3251-1
3. Empire of Blood (2005), ISBN 0-7869-3733-5
3. Ogre Titans
1. The Black Talon (2007)
2. The Fire Rose (2008)
3. The Gargoyle King (2009)

Dragonrealm

1. Series
1. Firedrake (1989), ISBN 0-445-20940-2
2. Ice Dragon (1989), ISBN 0-445-20942-9
3. Wolfhelm (1990), ISBN 0-445-20966-6
4. Shadow Steed (1990), ISBN 0-445-20967-4
5. The Crystal Dragon (1993), ISBN 0-446-36432-0
6. Dragon Crown (1994), ISBN 0-446-36464-9
7. The Horse King (1997), ISBN 0-446-60353-8
2. Origins
1. The Shrouded Realm (1991), ISBN 0-446-36138-0
2. Children of the Drake (1991), ISBN 0-446-36153-4
3. Dragon Tome (1992), ISBN 0-446-36252-2

Diablo

1. Diablo series
1. Legacy of Blood (2001), ISBN 0-671-04155-X
2. The Black Road (2001)
3. Kingdom of Shadow (2002), ISBN 0-7434-2692-4
4. Moon of the Spider (2006), ISBN 0-7434-7132-6
2. The Sin War series
1. Birthright (2006)
2. Scales of the Serpent (2007)
3. The Veiled Prophet (2007)

Warcraft

1. Series
1. Day of the Dragon (2001), ISBN 0-671-04152-5
2. Night of the Dragon (2008), ISBN 0-7434-7137-7
2. War of the Ancients
1. The Well of Eternity (2004), ISBN 0-7434-7119-9
2. The Demon Soul (2004), ISBN 0-7434-7120-2
3. The Sundering (2005), ISBN 0-7434-7121-0
3. Sunwell Trilogy
1. Dragon Hunt (2005), ISBN 1-59532-712-6
2. Shadows of Ice (2006), ISBN 1-59532-713-4
3. Ghostlands (2007), ISBN 1-59532-714-2
4. Independent Books
1. "Stormrage" (2010), ISBN 1-4165-5087-9

Independent

1. King of the Grey (1993), ISBN 0-446-36463-0
2. Frostwing (1995), ISBN 0-446-60149-7
3. The Janus Mask (1995), ISBN 0-446-60150-0
4. Dutchman (1996), ISBN 0-446-60151-9
5. Ruby Flames (1999), ISBN 0-671-03266-6
6. Beastmaster:Myth (2009)