Who votes for third party candidates? Can third party presidential candidates be “spoiler” candidates, ones who swing the election? I use the 2016 election to investigate this phenomenon. By examining datasets that asked participants who they would vote for in a two-way presidential race (between only Hillary Clinton and Donald Trump), versus who they would support in a four-way race (when Green Party candidate Jill Stein and Libertarian Party candidate Gary Johnson were added to the list of potential candidates), I can examine which voters change their support between the two-way and four-way races. In particular, I look at voters who support Clinton in a two-way race, but not in a four-way race; I label such individuals “Clinton switchers.” While this is only a modest fraction of the electorate, given Clinton’s razor narrow loss to Trump in Michigan, Wisconsin, and Pennsylvania, such shifts could have potentially altered the outcome. I hypothesized that different demographic and attitudinal groups of individuals would be more likely to switch their votes away from Clinton. In particular, I expected that younger, male, less educated, poorer, and non-swing state residents would be more likely to switch away from Clinton (as would Independent voters). Using both nationally-represented survey data (from CNN), and a survey of New York residents (from Siena Research Institute), I find support for all of the hypotheses mentioned above. This is important because it tells us what categorizes and defines the group of voters who ultimately caused the 2016 election outcome as well who are the people with a natural affinity for “spoiler” candidates in general.