There are several series in the manga, two of which have been released in America, one which CPM started releasing last September (2000). CPM finished releasing The Grey Witch, and the Lady of Pharis last summer. They started on the Chronicles of the Heroic Knight manga series this past September.
The first Lodoss manga released in Japan wass the Grey Witch, which came out when the OVAs were being released. It was followed by The Demon of Flame and the Lady of Pharis. The next one, Chronicles of the Heroic Hnight, was running in Kadokawa's Shounen Ace (Chinese Vers.: Tohan Boy's ACE), and is the story the TV series is based on. Welcome to Lodoss Island wass also running in Shounen Ace.

The Grey Witch: Came out during the release of the OAVs. It has a total of 3 graphic novels (about 170 pages each), and 22 chapters. It was released by Dragon Comics and again later by Kadokawa. The American version's release ended on chapter 22 in July 2000. It's released by CPM Comics and the third graphic novel is coming out soon. Story by: Ryo Mizuno, Art by: Yoshihiko Ochi.

The Demon of Flame: Ran for 2 graphic novels. Not sure about the storyline. It involes Parn and Deed, though. Published by Comp Comics.

The Lady of Pharis: Not sure how many GN this one ran. It was 8 issues; so probably one. Focuses on the original Six Heroes. Released in America by CPM. Story by: Ryo Mizuno, Art by: Akihiro Yamada.

Chronicles of the Heroic Knight: Based on novels 6 and 7, "Holy Knight of Lodoss" 1 & 2, and has run for a total of 6 graphic novels. It's the story the TV series revolves around after episode 8. It was running in Shounen Ace in Japan until August [2000] where it finished on chapter 38. The sixth and last GN hit stores in Japan on 9/30/2000. The manga went on for a few more months in Boys' ACE in Taiwan, and Hong Kong as it was a little behind Japan due to translating. Story by: Ryo Mizuno, Art by: Masato Natsumoto.

Welcome to Lodoss Island: The Lodoss Island manga was based on the 2nd novel, "The Demon of Flame" and has run for 2 GNs up to this point. It was sort of an expirimental to begin with, but it has become pretty sucessful because of the Welcome to Lodoss Island movie. It was also serialized monthly in Shounen (Tohan Boys') Ace.

Deedlit's Tale: This is a shoujo (girls) manga that began it's run (in the US) in September 2001, and has run, as of February [2002] for 7 issues under CPM Manga. It's a [non-continuous] story that explores Parn and Deed's relationship, and introduces several new characters. Story by: Ryo Mizuno, Art by: Setsuko Yoneyama.