The East Coast Bays by-election of 1980 was a by-election during the 39th New Zealand Parliament. It was prompted by the resignation of Frank Gill, a National Party MP, to take up a position as New Zealand's ambassador to the United States. It resulted in the election of Gary Knapp, the candidate of the Social Credit Party. This result was unexpected, as minor parties rarely won seats in Parliament at the time (although such voting is more likely in a by-election).