A company called Reaper Miniatures produced miniatures based on Doom & Doom II characters from September 1997 to July 1999. The line featured miniatures of Marine with Shotgun (Hero), Zombie Marine with Autorifle, Zombie Marine with Shotgun (Sergeant), Heavy Weapons Dude (Chaingunner), Imp, Pink Demon, Lost Soul, Cacodemon, Pain Elemental, Revenant, Mancubus, Baron of Hell, Arachnotron, Arch-Vile and Cyberdemon. Reaper part numbers were 66601 thru 66615 (in respective order from above).
The miniatures were produced under a licence from id Software.
Three of the miniatures - the Baron of Hell, Mancubus, and Pinky Demon - were offered as Doom 3 preorder bonuses (which were actually possible to obtain for free by reserving the game, getting the miniature at the time of reservation and cancelling the preorder). GameStop, EB Games, and Best Buy each had one as their own store exclusive. Note that Best Buy also offered to sell their miniature online for $10 for those who did not wish to preorder the game.
The original miniatures were carved by 3 freelance artists contracted by Reaper: Sandra L. Garrity, Julie Guthrie, and Bob Ridolfi. Sandra carved 9 of them, Julie 2, and Bob 4.
In addition to the published line of figures, two extremely limited prototypes of the Cyberdemon miniatures were also cast. Neither were ever released to the public market as they were rejected by id Software during the miniature line's approval process due to being too small and having a pose they did not like. According to Ed Pugh, co-owner of Reaper Miniatures, 15-20 of each prototype exist worldwide. Each of the two prototypes were given to all current id employees, and over the years a very few of those have found their way onto the open market.
Also, the Arachnotron was originally rejected by id as the brain was not round enough and was actually rather flat on top, among other small issues id had with its design. Unlike the prototype Cyberdemons, there was only one of the rejected Arachnotron's ever produced. It sat in the office of David Pugh (co-owner of Reaper) until April 2010, at which time it was acquired by a private collector.
In addition to the Demon, Baron of Hell, and Mancubus being released with Doom 3 pre-orders, the Lost Soul was also released with a Doom 3 pre-order in the Australian market. Why it was released only in Australia and not worldwide, no one seems to know.
You can tell the difference between the original release from 1997 and the re-release for Doom 3 by looking at the bottom of the miniature. The originals all have "TM 1996" molded onto the bottom. The re-releases all have "1993, 1997" on the bottom.