Today [Apr 21 '16] and yesterday there were a considerable number of suggested edits to previously empty tag wikis and tag wiki excerpts (browse here; viewing the full list requires >=10K points, I think), all by the same user. These edits mostly didn't really follow the guidelines on writing good tag wikis, in particular they often didn't make clear which questions should have the particular tag. On the other hand, having a tag wiki may be considered better than having no tag wiki, at least unless the contents are too unreasonable. It happens that these tag wiki edits were accepted by some users (like myself, at least in most cases -- though I don't know whether this was the 'right' choice), and rejected by others. -- Any opinions?
The problem seems to be more serious: the tag wiki edits by this user seem to copy-paste material from sites like MathWorld, which requires a license for commercial use (http://mathworld.wolfram.com/about/faq.html#copyright), for example, https://mathoverflow.net/tags/axiom-of-choice/info is copy-pasted from http://mathworld.wolfram.com/AxiomofChoice.html.
Some other tag wiki edits by this user copy-paste material from Wikipedia, which allows commercial use, but requires attribution. However, no attribution is given. For example, https://mathoverflow.net/tags/calculus-of-variations/info is copy-pasted from https://en.wikipedia.org/wiki/Calculus_of_variations.
As pointed out in the question, the problematic tag-wikis came mostly from a single user. Since this user has deleted his account in the meantime, they can be no longer found through his profile page. (In case somebody wants to help and improve the tag-wikis which are still missing source/attribution.)
To help with this problem, here are a few SEDE queries which might help to find them: