The Wizard, Fighter, Dwarf and Henchman were released in a Preview Pack, unfortunately the Elf wasn't, and is accordingly rare. The Wizard piece was given away in White Dwarf to promote Mordheim, and is the most common.
And yes, they should be on round bases for AHQ, so sue me...
Painter:
Metal versions: Adam Skinner, Plastics: Phil Lewis, Henchman: Orclord
Advanced Heroquest Prototypes
Dwarf
Elf
Fighter
Henchman
Wizard
Skaven
Advanced Heroquest Prototypes & Plastics
Advanced Heroquest Plastics