David Catania, who has been a member of the Washington, D.C. city council since 1997, will run for Mayor as an independent this year. See this story.
He was first elected in a special election in 1997 as a Republican to an at-large seat. Because the election was a special election, parties did not have nominees. Catania faced two Democrats and a Socialist Workers Party candidate, and won with 43% of the vote.
He was re-elected as a Republican in 1998 and 2002. In those races, he was helped by a D.C. election law that lets the voters choose two at-large members in any single election year, but forbids any party from running more than one nominee. The intent of this law is to prevent one party from winning all the Council seats. In 2004 he left the Republican Party and became an independent. He was re-elected as an independent in 2006 and 2010.