Coca-Cola announced this week that Herb Allen, 80, has retired from its board of directors, where he has served for 39 years, working with six different Coke chief executive officers.

For much of his tenure, he was considered among the most powerful and involved directors overseeing the Atlanta-based beverage giant. He sometimes played an outsized role in who was chosen to lead the company and what businesses Coke tried to acquire. Fortune magazine once referred to Allen and then-director Warren Buffett as the Coke board’s “800-pound gorillas.”

Allen was one of only three people serving on the Coke board’s executive committee, and he chaired the management development committee, responsible for oversight of talent development of senior leaders and succession planning.

The company did not offer a reason for the timing of Allen’s retirement, which was announced only four months after shareholders overwhelmingly reelected him and other directors to new one-year terms. His departure was effective Aug. 18 and leaves Coke with 11 directors.

Allen is chief executive officer of Allen & Co., a New York-based, privately held investment firm. He joined the Coke board in 1982 after selling Columbia Pictures to the company. The company’s movie business struggled, but Coke made big gains when it sold Columbia in 1989.

Allen holds about 18 million shares in the company, either directly or through Allen & Co., according to a filing earlier this year with the Securities and Exchange Commission.