John Roger Davis Jr. (born July 25, 1927) is a retired American diplomat. From 1988 to 1990, he served as the United States Ambassador to Poland, where he helped guide Solidarity, and Poland, in its quest for free elections. Later, from 1992 to 1994, he served as the United States Ambassador to Romania. Former Director of National Intelligence Dan Coats named Davis as the fourth person – after Lech Walesa, Mikhail Gorbachev and Pope John Paul II – who had “the most critical role in bringing about the collapse of communism in Eastern Europe”.