Dawn E. Pettengill (born July 2, 1955) is an American retired politician from Iowa. She was a member of the Iowa House of Representatives from 2005 to 2019, where she represented the 75th District (numbered as the 39th District until January 2013). On April 30, 2007, she switched to the Republican Party, having previously served in the House as a Democrat. In a letter to her constituents, Pettengill said she decided to switch parties due to disagreements with fiscal and labor policy, as well as the state Democratic Party's decision to take her off the incumbent protection list for the 2008 elections.