The Watergate scandal was a major political scandal in the United States involving the administration of President Richard Nixon from 1972 to 1974 that led to Nixon's resignation. The scandal stemmed from the Nixon administration's persistent attempts to cover up its involvement in the June 17, 1972 break-in of the Democratic National Committee headquarters at the Washington, D.C., Watergate Office Building.
Who were the major players in the Watergate conspiracy?
The list begins with the President of the United States, Richard Nixon. John Dean served as the Counsel to the President, and was a lead witness whose testimony blew the case wide open, naming many top presidential aides as being closely involved. H.R. Haldeman, John Ehrlichman, and John Mitchell were all senior members of the administration who resigned in disgraced and were convicted. Howard Hunt and G. Gordon Liddy played major roles in the Watergate break-in. 

A major figure in the conspiracy was Daniel Ellsberg, but not for any wrongdoing. Rather, he was a target of the Nixon White House, and an attempted burglary of his psychiatrist's office was just one of the illegal acts that the White House covered up.