100 Most Influential People in Healthcare – 2016

• Years on list: 2

Brennan has been a key figure for the pharmaceutical giant as it continues to expand efforts to improve overall health for individuals. The company stopped selling tobacco products at all its 7,800 drugstores in October 2014 and has partnered with health systems under its MinuteClinic brand. Before joining CVS, Brennan was chief medical officer of Aetna, where he oversaw all clinical policies and patient management services. He was also president and CEO of Brigham and Women's Physician Group.