Hugh Roy Cullen was born in Denton County on 3rd July, 1881. He received only a few years of education. At the age of sixteen Cullen began work with a cotton broker. Later he started a real estate business.
In 1911 Cullen moved to Houston and eventually went into the oil business. He made major discoveries at Pierce Junction, Blue Ridge, Rabb's Ridge and Humble. Cullen became a co-owner of the South Texas Petroleum Company and later established the Quintana Petroleum Company.
Cullen was active in Texas politics. In 1944 he became a leading figure in what became known as the Texas Regulars movement. Cullen was the main provider of funds for this group that included Eugene B. Germany, Wilbert Lee O'Daniel and Martin Dies. This was a group of right-wing members of the Democratic Party who opposed the liberal policies of Franklin D. Roosevelt. Supported by Texas oilmen, the group were also opposed to the fixed prices of oil and gas imposed by Roosevelt's government during the Second World War. They also campaigned against the New Deal, civil rights and pro-trade union legislation. The group disbanded after they failed to remove Roosevelt as the leader of their party.
Cullen survived the Great Depression and in 1947 he was able to establish the $160 million Cullen Foundation. This provided money for education and medicine. Cullen also gave more than $11 million to the University of Houston.
In 1948 conservatives like Cullen were opposed to Harry S. Truman and his Fair Deal proposals that included legislation on civil rights, fair employment practices, opposition to lynching and improvements in existing public welfare laws. When Truman won the nomination, Southern Democrats formed the States' Rights Democratic Party (Dixiecrats) and Storm Thurmond was chosen as its presidential candidate. It was thought that with two former Democrats, Thurmond and Henry Wallace standing, Truman would have difficulty defeating the Republican Party candidate, Thomas Dewey. However, both Thurmond and Wallace did badly and Truman defeated Dewey by 24,105,812 votes to 21,970,065.
In 1952 Cullen gave his support to Dwight D. Eisenhower and the Republican Party. His main political concern was in the preservation of the oil depletion allowance. He was therefore pleased by Eisenhower's decision to employ Robert Anderson (the former president of the Texas Mid-Continent Oil and Gas Association) as Secretary of the Navy and Secretary of the Treasury. In this post Anderson introduced legislation beneficial to the oil industry.
Cullen was also a great supporter of Joseph McCarthy. In 1952 he was the single biggest contributor to McCarthy's reelection campaign. His friends Jesse H. Jones and Clint Murchison were also financial supporters of McCarthy. As Murchison pointed out in 1954: "We all made money fast. We were interested in nothing else. Then this communist business suddenly burst upon us. Were we going to lose what we had gained?"
Hugh Roy Cullen died in Houston on 4th July, 1957.