This happened after I had trouble importing such a character into the Unreal Engine 4.
The Unreal Engine 4 accused the following problem: Multiple roots are found in the bone hierarchy we only support single root bone
Following the answer to this question (https://answers.unrealengine.com/questions/109814/multiple-roots-are-found-in-the-bone-hierarchy-we.html), I was able to get the object imported correctly to Unreal Engine 4.
Transcript of the answer (I quoted the link)::
First, unparent your mesh to the skeleton (or this may cause crashing later when importing) alt+p, clear parent. Now, go and create a root bone if you do not already have one you want to use as root. Join all your bones together into one armature by selecting them all in object mode and pressing ctrl+j. Select the armature and go to (usually tab)edit mode, select all the bones that you ARE NOT your root bone, then finally select the root bone and press ctrl+p (make parent), and select keep offset, (assuming you dont want to move your other bones onto the root bone). Export the armature as fbx as you where and it should work now.
Returning to Blender:
Note that it not only separated the mesh from the armature, as you can see that the bones are showing two poses at the same time (in object mode):
I would like you to tell me the correct way to put the 2 together again, so that after that I can import into the Unreal Engine 4.