In a comment to my question about published papers that originated on math.SE Asaf asks about master's theses. I think it would be interesting to have a list of those as well. So, that's what this thread is for: A list of master's theses and doctoral dissertations that originated on math.SE.
As with the question about papers, perhaps each answer could link to a question or answer on the main site, along with a brief summary of the content of the thesis or dissertation.