MCLEAN, Va. — Forrest E. Mars Jr., heir to candy giant Mars Inc. and its former co-president, has died at age 84.

Forrest E. Mars Jr.

Mars Jr., who passed away on July 26, was the eldest son of Audrey and Forrest E. Mars Sr. and the grandson of Frank C. Mars, the founder of Mars Inc. With his brother John and sister Jacqueline, Mars Jr. inherited a significant business and grew it into one of the world’s largest and most respected family firms.

Forbes reported that Mars Jr., at the time of his death, had a net worth exceeding $25 billion, making him the 16th-wealthiest person in the nation and 25th-wealthiest person in the world.

“Forrest was a great inspiration to all of us at Mars Inc.,” Grant Reid, chief executive officer and Office of the President for Mars Inc., said in a statement. “He was instrumental in building our business while remaining committed to the founding principles of the company. Forrest will be sorely missed, but his contributions and the legacy he leaves behind at Mars will be long-lasting.”

Mars Jr. was born in 1931 in Oak Park, Ill., and earned a Bachelor of Science degree from Yale University in 1953 and an M.B.A. from the New York University School of Business in 1958. He began his career in 1955 as a certified public accountant, working as an auditor for Price Waterhouse after serving in the United States Army for two years. He joined Mars Inc. as a financial staff officer for M&M’s Candies in 1959, when the company was a business of less than $100 million in revenue.

Two years later, Mars Jr. was named general manager of a new confectionery factory to be built in Veghel, the Netherlands, a move that proved to be the first step of Mars’ global expansion. Beginning with five associates, he oversaw construction of what is now one of the world’s largest chocolate factories in the world. He managed the factory until 1966, when he moved with his family to Neuilly-sur-Seine, outside Paris, to become managing director of Mars France.

During Mars Jr.’s four-year tenure in Paris, the company expanded its pet food business via the 1967 acquisition of Unisabi, creating a foundation for future growth in France that continued well into the 21st century with the 2002 acquisition of Royal Canin.

Mars Jr. moved to McLean, Va., in 1970 to assume responsibility for Mars’ confectionery operations as group vice president. In McLean, he worked with his brother, John, also a group vice president, who managed the company’s pet food, vending and money systems operations. Eventually, the brothers took joint responsibility for all company functions and became co-presidents of Mars Inc. in 1975, at which time the company’s net sales were just over $1 billion. Over the course of their leadership, they continued to expand into new markets and launch new brands.

Today, Mars Inc. has sales of $35 billion from six business segments — chocolate, Wrigley, pet care, food, beverages and Symbioscience — and provides 80,000 jobs in 78 countries. Its roster of brands includes Mars, M&M’s, Snickers, Milky Way, Dove, 3 Musketeers, Twix, Doublemint, Extra, Orbit, Skittles, Starburst, LifeSavers, Altoids, Uncle Ben’s, Alterra, Flavia, Cocoavia, Pedigree, Whiskas, Iams, Eukanuba and Royal Canin, among others.

After his retirement as an associate in 1999, Mars Jr. continued to provide guidance and counsel to Mars business leaders, according to the company. He served as a member of the board of directors until 2006, working on the audit and remuneration committees, and he remained active in the Mars Foundation.

He also was a leading philanthropist, locally and internationally, supporting environmental preservation projects, such as the American Prairie Reserve, and many projects in support of American history, such as the Brinton Museum of Western and American Indian Art in Big Horn, Wyo., and the Mars Hall of American Business at the American History Museum.

Mars Jr. is survived by his wife, four children, 11 grandchildren and two great-grandchildren.