Claim: H. H. Holmes was a serial killer.

Herman Webster Mudgett -LRB- May 16 , 1861 -- May 7 , 1896 -RRB- , better known under the name of Dr. Henry Howard Holmes or more commonly H. H. Holmes , was one of the first documented serial killers in the modern sense of the term .   While he confessed to 27 murders , only nine could be plausibly confirmed and several of the murders he confessed to were people who were still alive . He is commonly said to have killed as many as 200 , though this figure is traceable only to 1940s pulp magazines . Many victims were said to have been killed in a mixed-use building he owned , located about 3 mi west of the 1893 Chicago World 's Fair and said to have been a World 's Fair Hotel , though evidence suggests that the hotel portion was never truly open for business .   Besides being a serial killer , Holmes was also a successful con artist and a bigamist , the subject of more than 50 lawsuits in Chicago alone . Many now-common stories of his crimes sprang from fictional accounts that later authors took for fact ; however , in a 2017 biography , Adam Selzer wrote that Holmes ' story is `` effectively a new American tall tale - and , like all the best tall tales , it sprang from a kernel of truth '' .