Dennis Gillings was born in London, England near the end of World War II. His father was a wholesale fish merchant who fought in the D-Day invasion, while his mother was a homemaker and milliner. During his adolescence, Gillings attended the Coopers’ Company School. He received his bachelor’s degree in mathematics from the University of Exeter and then received his diploma in mathematical statistics from Cambridge University. Gillings returned to the University of Exeter for his PhD, where his thesis was on mathematical models in health services. In 1971, Gillings was hired by the University of North Carolina at Chapel Hill to be an assistant professor in biostatistics. After a road trip across the African continent, Gillings left England for the United States. At Chapel Hill, Gillings became the associate director of the campus’s health services research center. He was approached by the pharmaceutical company Hoechst-Roussel to help them introduce their anti-sulfonylurea to the United States. This inspired Gillings to create a program at Chapel Hill in which graduate students would be paid to assist him in his consulting work.

Gillings continued his consulting work alongside his professorship until 1988, when he left Chapel Hill to form his own clinical research company, Quintiles. The company’s focus was primarily on analysis and data management, eventually expanding across the United States and then to Europe in 1993. Gillings took Quintiles public in 1994, after which Pamela Kirby replaced Gillings as the CEO. After economic issues, though, Gillings returned as CEO and privatized the company again. Quintiles continued to grow, seeing its revenue grow three times and its profits five times when the company went public again in February 2013. Gillings’s work and service to the pharmaceutical industry was honored in 2004 when he was appointed Commander of the Order of the British Empire.