Guccifer 2.0 is the name claimed by a person or person who hacked the DNC and probably other web sites associated with Hillary Clinton. It is not to be associated with Guccifer, an actual hacker now in US custody, as William Watson does below.
It is generally believed that Guccifer 2.0 is not a real hacker, and is just a fictional person created by Russian intelligence agencies to disguise their involvement with the hack. There are several reasons for this:
‘Guccifer 2.0’ Is Likely a Russian Government Attempt To Cover Up Their Own Hack
A Romanian hacker, whose name is Marcel Lazar Lehel, who is currently in jail in Virginia because the U.S. Government does not want anybody to know what they’re up to. Before exposing the Democratic National Committees commitment to nominate Hillary Clinton, regardless of how people voted, he was known for exposing the art works of former president George W. Bush. In my opinion, he’s a hero. Whether you agree with me or not depends on what you think of Edward Snowden and Julian Assange. If you like them, you should like Guccifer, too.