Markus Heitz (born October 10, 1971 in Homburg) is a German fantasy, horror and science fiction author. With more than 5 million books sold in Germany alone, Heitz is considered one of the most successful German fantasy authors.

After graduating from the private Catholic school Johanneum in Homburg in 1991 and completing his basic military service in Bexbach the following year, Heitz studied German and history until 2000, first as a teacher and then with a master's degree. The Protestant then worked as a freelance journalist for the Saarbrücker Zeitung. Since his breakthrough in 2003, he has been working as a freelance author.

Heitz published his debut novel Die Dunkle Zeit 1 - Schatten über Ulldart in 2002, for which he was awarded the Deutscher Phantastik Preis in the category Best Novel Debut National in 2003. His final breakthrough came with the novel Die Zwerge in 2003.
In 2005, Heitz revived the adventure game book, a popular genre of the 1980s, in collaboration with the publisher Pegasus Press. Here, the reader decides for themselves how the main character should proceed in order to complete an adventure. Since then, gamebooks have been published with plots set alternately in the worlds of the Ulldart novels and the Dwarf novels. The author of the first two gamebooks was Heitz himself, the later ones were created in collaboration with Nicole Schuhmacher (adventure gamebook in the Dwarves' Hidden Land) and Sonja Rüther (adventure gamebook in Ulldart).

The Justifiers role-playing game system was developed in the USA in 1988. Markus Heitz secured the rights and, together with other authors, developed a modernized version of the role-playing game, which has since been discontinued. A series of novels and comics based on the game has also been discontinued.

Between 2002 and 2005, Heitz wrote a total of six novels and a short story for the Heyne series on the Shadowrun role-playing game. The two anthologies Schattenjäger and Schattenläufer bring together the six loosely connected novels.

As a guest author, Heitz wrote volume 2615 of the Perry Rhodan series under the title Death Hunt for Rhodan, which was published in 2011 for the Perry-Rhodan-WeltCon on the occasion of the series' fiftieth anniversary.
Heitz wrote the libretto for "Timm Thaler - Das Musical" with music and lyrics by Xavier Naidoo and Michael Herberger, which was published by Gallissas Theaterverlag in 2012. The musical is based on the novel Timm Thaler by James Krüss.

In 2020, the thriller Die Republik, which is set in an alternative history world in which the GDR comprises the entire territory of Germany apart from West Berlin, was published under the pseudonym Maxim Voland. Heitz explained this step as a way to better differentiate future works in the thriller/crime genre from his focus on fantasy and horror.