Can you replicate characters from games? PLEASE I WANT TO KNOW
There are already commercial services that you can point at your WoW account and pose your character and choose weapons to hold, etc, then receive a 3d printed miniature.
Can you, definitely. Should you, possibly. Should you do it for commercial purposes, not unless you enjoy spending time in a courtroom and losing as it will almost certainly be seen as a copyright violation as a derivative work.
For personal use there are a number of tools to help you extract the 3d model from the game, but there will probably be quite a bit of work required to clean them up to a printable format.
Most - if not all - games with a modding community have various software to extract the 3d models from the game files. Some models are pretty much ready to print, others need tweaking, splitting up or manual support structure.
UE viewer http://www.gildor.org/en/projects/umodel reads files from games made with unreal engine for instance.