He most recently had been leading the Highland Consumer Fund, a venture capital and growth equity group focused on consumer companies. Investments included Pinkberry and Lululemon (LULU). In a conversation with Fortune a couple of months back, he had expressed interest in raising a new fund.

At last check, Stemberg was serving on the boards of directors at Lululemon, CarMax, Inc. (KMX), DAVIDsTEA (DTEA), Guitar Center, Indochino, J.McLaughlin and Pharmaca.

Stemberg most recently made headlines in 2012 as a speaker at the Republican National Convention, in support of Mitt Romney, who had been an early Staples investor while with Bain Capital.

In a statement to The Boston Globe, Romney said: “Tom is one of the great business leaders of our state and our nation. He was not only the founder, but someone who grew the company to a multi-billion dollar enterprise. He built an industry that employs thousands and thousands of people.”

He had opened the first Staples store in Brighton, Mass. in 1986. It currently has more than 1,600 stores in North America, and a market cap north of $8 billion. Staples recently agreed to merge with Office Depot, in a deal that is receiving close scrutiny from federal regulators. Back when Stemberg was still Staples chairman in 1997, a similar merger was blocked due to antitrust concerns.

The office supply retailer has not yet replied to requests for comment.

Update: Staples chairman and CEO Ron Sargent just issued the following statement:

“Tom was a great friend, mentor and colleague to many of us, and he will be greatly missed. Tom was a visionary who invented the office products superstore and turned it into a global industry. He had great energy, determination, and an incredible passion for our business. His entrepreneurial spirit and legacy will live on through the many people he inspired and the company he created. On a personal note, I’ll remember Tom for his great sense of humor, and most of all, his caring nature.”

Highland Capital Partners, the venture capital firm with which Stemberg’s Highland Consumer Partners was affiliated, also provided the following:

“The partners and staff at Highland Capital are terribly saddened by the loss of our very close friend and longtime colleague, Tom Stemberg after a long and courageous battle with cancer. Tom joined Highland in 2005, and became a founding General Partner of the Highland Consumer fund in 2007. Since that time we have come to know and love him as a partner, as a committed philanthropic member of our community and as a business pioneer and leader across the globe. Words cannot convey how deeply we will miss his intellect, humor and friendship. Our thoughts and prayers go out to the entire Stemberg family and to all who he touched.”