The Art of the Dungeons & Dragons Fantasy Game focuses on the heavyweights of the day: Easley, Elmore, Parkinson, and Caldwell. Thankfully, there’s also quite a selection of Timothy Truman, who I think is generally underrated. Almost all of the art above, most of it Truman’s, is sourced as “product design,” referring to the AD&D LJN toys released in 1983.
Many of Truman’s illustrations made it onto the action figure and adventure figure (PVC) cards, including the popular first series releases Warduke (Evil Fighter), Elkhorn (Good Fighter Dwarf), Zarak (Evil Half-Orc Assassin), and Melf (Good Fighter Elf). The same illustrations appear later in Quest for the Heartstone (1984), a module that includes many of the characters from the LJN line (and others that were meant to be part of the line but didn’t make the cut).
Truman’s gnoll illustration (sixth image down) is originally from Return to Brookmere by Rose Estes (1982), an Endless Quest book. His Orc (third image down) appeared on the back of the Orcs of the Broken Bone adventure figure card (below). His awesome Skeletal Warrior did not, for some silly reason, appear on the back of the Skeleton Soldiers of Sith card. The less awesome substitute is below.
There’s a nice trio of inks by Jeff Easley (seventh image down), also sourced as product design. I’m not sure if or when they were published.
2 Warps to Neptune 
Holy Crap! THE LICH! Cartoon Network’s Adventure Time (which my kid and I watch all the time) has a character called The Lich! Pretty darn creepy, too. Perhaps one of the producers was/is a D&D fan? That’s random!
Dude, liches are fantasy staple since 1978. 🙂 D&D used them first but they have been in pretty much every RPG since, from Heroes of Might and Magic to Warcraft.
The lich design may have been altered from this to his final toy design, possibly because it was deemed too scary for kids? Anyway, this design is very cool.