This is the Wizard from the Grenadier Wizards Box Set 2001. This guy, like most of the other minis I have from this set, was sandblasted a long time ago to remove a paintjob I did in junior high school. So I had to try to paint back in some of the detail.
I think the creature on his shoulder is an imp. Back in the original Advanced Dungeons and Dragons, a magic-user (as wizards were generically called in that edition) could have one of 4 special familiars, if they were really lucky. Which special familiar you could get depended on the character’s alignment. The familiars were Brownie, Pseudo Dragon, Quasit, and Imp. Imps were only available to lawful-evil or neutral-evil magic-users. Looking up those four creatures in the Monster Manual shows that the imp is the only one that looks much like the critter sitting on this guy’s shoulder.