Guillermo Endara (born 1936) was a member of the Panameñista Party and an ally of Arnulfo Arias for many years prior to his installation as president of Panama by the U.S. Government in 1989.

Guillermo Endara was installed as president of Panama in the Christmas 1989 invasion (Operation Just Cause) by U.S. military forces sent to depose General Manuel Noriega. Until May 1989 Endara was virtually unknown to Americans. Then he became the presidential candidate of the Panameñista Party and the choice of Noriega's growing middle-class opposition, the Civil Democratic Opposition Alliance. Foreign dignitaries (among them former U.S. President Jimmy Carter) who monitored the May 7, 1989, election agreed that Endara won decisively. But Noriega ordered seizure of the ballot boxes and subsequently declared the election void and sent his goon squad (the Dignity Battalions) to harass the opposition, many of whom had taken to the streets...