William Victor Roth, Jr. (July 22, 1921 - December 13, 2003) was a United States Representative and five-term Senator from Delaware. A member of the Republican Party, he served in the House from 1967 to 1970 and in the Senate from 1971 to 2001.

Born in Great Falls, Montana, Roth attended public schools in Helena and graduated from the University of Oregon in 1943 and Harvard Business School in 1947. In the interim, he served in the United States Army from 1943-46. Roth moved to Delaware in 1954 and made it his adopted state.

Roth is best remembered as a strong advocate of tax cuts, and he co-authored the Kemp-Roth Tax Cut in 1981 with Jack Kemp. Roth was also the legislative sponsor of the individual retirement account plan that bears his name, the Roth IRA, and was known as a fiscal conservative. He was defeated in the 2000 election by the Democratic candidate, former Governor Thomas Carper.