These are the essential comics and novels for any true fan of the Sith Lord, Darth Maul.
Star Wars: The Wrath of Darth Maul: This is the ultimate source for anyone who wishes to learn about Maul's origin story. You'll find out about his training, his relationship with his former Master, Darth Sidious, as well as all about who Maul is as a character. This novel reveals a ton about Maul's past and shows how he got to where he is today, during The Clone Wars. An absolutely essential read.
Maul as a Sith Lord and Assassin
Star Wars: Darth Maul: Maul took on many covert assignments from his Master during the years between him becoming a Sith Lord, and The Phantom Menace. In this comic series, you will see Maul take on the Black Sun, an extremely powerful crime syndicate whose influence spans over nearly all of the known galaxy.