William Pettus Hobby Jr. (born January 19, 1932) is an American politician who served a record eighteen years as the 37th lieutenant governor of Texas, from 1973 to 1991. He was the last lieutenant governor to serve a two-year term and the first elected to a four-year term, following the amendment to the Texas Constitution that lengthened terms for statewide elected officeholders to four years, effective with the 1974 elections.

Hobby was born in Houston, Texas, the only son of William P. Hobby Sr. and Oveta Culp Hobby. Both of his grandfathers were in the Texas Legislature. His father was also a lieutenant governor of Texas and the governor from 1917 to 1921, and his mother was the first person appointed to the new position of United States Secretary of Health, Education, and Welfare by U.S. President Dwight D. Eisenhower, a Republican. She served in that position, now the United States Department of Health and Human Services, from 1953 to 1955.

Hobby attended high school at St. Albans School in Washington, D.C., he then attended Rice University in Houston. After graduating in 1953 with a Bachelor of Arts, he served in the United States Navy for four years in naval intelligence.

For many years, the Hobby family owned the now-defunct Houston Post, at which Hobby worked. He worked his way through the editorial department. When his father became ill in 1963, Hobby assumed editorial and managerial control of the newspaper. He remained president of the Post for twenty years – until the family sold the newspaper in 1983. It was absorbed in 1995 by the Houston Chronicle, which is still published.

Hobby's lengthy career in government began in 1959, when he served as parliamentarian of the Texas Senate under Lieutenant Governor Ben Ramsey. He was appointed to the Presidential Task Force on Suburban Problems and to the National Citizens Advisory Committee on Vocational Rehabilitation by U.S. President Lyndon B. Johnson. Governor Preston Smith appointed him to the Texas Air Control Board. Lieutenant Governor Ben Barnes appointed him chair of the Senate Interim Committee on Welfare Reform in 1969. Hobby resigned from the Texas Air Control Board in 1971 to run for lieutenant governor.

Hobby was elected lieutenant governor in November 1972 with 93 percent of the statewide vote, having defeated token opposition, not from a Republican but from the Hispanic former third party, Raza Unida, which ran Alma Canales of Edinburg even though she did not meet the age requirement for the office. The position had opened when the two-term incumbent, Ben Barnes, ran unsuccessfully in the Democratic gubernatorial primary and finished in third place. Hobby was an easy winner in most of his elections, including a high-profile race in 1982 in which he defeated the Republican nominee George Strake Jr., also a Houston businessman, a former Secretary of State of Texas, and later the Republican state chairman. Hobby was re-elected in 1974 (when the term was extended to four years), defeating Republican Gaylord Marshall. Hobby polled 1,170,253 votes (74 percent) to Marshall's 379,108 (24 percent) and in their 1978 rematch with Hobby polling 1,434,613 votes (64.91 percent) to Marshall's 760,642 votes (34.42 percent), 1982 defeating Strake with Hobby polling 1,830,870 votes (58.35 percent) to Strake's 1,272,644 votes (40.56 percent), and 1986 defeating David Davidson with Hobby polling 2,032,781 votes (61.37 percent) to Davidson's 1,231,858 votes (37.19 percent). Hobby did not seek an unprecedented sixth term in 1990, and the lieutenant governorship passed to fellow Democrat then-Comptroller Bob Bullock on January 15, 1991.

In addition to presiding over the state senate, Hobby served in numerous other leadership capacities within the political sphere. These included appointments as chair of the Governor's Energy Advisory Council (GEAC) (1973–1977), the Texas Energy Advisory Council (TEAC) (1977–1979), the special advisory committee which recommended the Texas Sunset Act (1970s), and the Joint Advisory Committee on Educational Services to the Deaf (1976–1979); co-chair of the Texas Energy and Natural Resource Advisory Council (TENRAC) (1979–1983); vice-chair of the Criminal Justice Policy Council; ex officio member of the Texas Advisory Commission on Intergovernmental Relations; and member of the Select Committee on Public Education (1983–1984). He was also chair of the National Conference of Lieutenant Governors in 1974. In 1985, he joined the mental health activist, Helen J. Farabee of Wichita Falls, in convincing the legislature to create the Department of Mental Health Mental Retardation, known as MHMR.

"Over his years as Lieutenant Governor, Hobby gained a reputation as an astute fiscal manager and parliamentary leader in the Texas Senate," according to a biographical sketch in the state archives.