The Create-A-Monster line of doll parts was introduced to the franchise in late November, 2011. The line was inspired by fans' enthusiasm for making their own characters and adding them to the Monster High student body in personal play. From early on, Monster High has attracted astounding artists who made their characters into dolls by retooling and repainting official dolls. With Create-A-Monster, Mattel targets the less-experienced part of the fanbase, encouraging people to make and remake their own dolls from the parts sold.
Create-A-Monster comprises seven types of products to create personal dolls. Starter packs contain two sets of parts for dolls of different species. Originally, the starter packs come with only one set of shoes, one wig, and one torso, meaning that only one doll at a time can be made from the materials in one starter pack. Half a year later, the starter packs were changed to include two torsos, which isn't enough for a full doll still, but makes it easier to finish up the second doll with own means. Add-on packs contain one set of parts for one type of monster. These packs contain no upper arms, upper legs, or torsos, meaning that a starter pack has to be purchased to make a doll with add-on pack parts. Mattel also shortly made a special Torsos set available through their website. This set contains matching torsos and upper limbs for the first two starter packs and the first three add-on packs. Create-A-Monster also has playsets in its ranks, both specifically designed for an extra kind of Create-A-Monster experience. The Design Lab and its Design Lab add-on packs contain dolls without sculpted face, but with tattoos to create the faces and decorate limbs. The Color Me Creepy Chamber and its two types of add-on packs contain dolls and clothes which respond to temperature with color change, allowing for designs to be made by making certain portions of the doll warmer or colder than the rest. One type of add-on pack consists of temperature-sensitive doll parts with non-sensitive clothes, and the other type of add-on pack consists of temperature-sensitive clothes.
The Create-A-Monster line is praised for the creative possibilities it adds to Monster High dolls, but it also is criticized for forcing people to buy multiple packs. With only an add-on pack, no doll can be made, and with a starter pack, only one doll can be made. Originally, if one were to combine an add-on pack and a starter pack, only one doll could be created, while two almost-full sets of part are rendered useless. Mattel has responded to this critique by adding a second torso to the newer starter packs, including the re-released original starter packs. Though this does not solve all problems, it does allow for two dolls to be made at a time from a starter pack and add-on pack combination.
It has been noted by the fandom that Create-A-Monster releases somewhat predict regular doll releases monster-wise. For instance, the November 2011 dragon and skeleton were followed by the releases of Jinafire Long and Skelita Calaveras in November 2012, while the trademarks were requested in June 2012. And a similar thing appears to be happening with the 2012 gorgon and the supposedly 2013 release of Viperine Gorgon. While it would make sense for Mattel to try new monsters first with a Create-A-Monster set, which don't require character investment, to generate or test interest, this connection between the Create-A-Monster line and regular dolls is not sufficiently proven yet, and Create-A-Monster releases can only be viewed as low-risk expansions of the franchise's monster world.