Samuel J. Heyman (March 1, 1939 – November 7, 2009) was an American businessman and hedge fund manager best known for his longtime chairmanship of the GAF Materials Corporation and International Specialty Products Inc. (ISP).

[2] As an undergraduate at Yale College, Heyman was a regionally ranked varsity tennis player and member of Phi Beta Kappa.

In late December 1983, the shareholders voted to oust the existing Board (including Werner) and to install Heyman as CEO and chairman.

At the time, given Heyman's minority ownership of less than 5% of the company, Barron's hailed the development as "one of the most striking achievements in the annals of corporate finance.

This investment style led GAF Corporation to pursue the attempted hostile takeovers of Union Carbide in late 1985 (Union Carbide's stock had cratered as a result of the December 1984 Bhopal incident) and Borg-Warner in April 1987 (Borg Warner's stock was substantially undervalued due to the poor performance of its automotive business, which masked the exceptional performance of its chemicals business); these investments were operationally justified by Heyman in the public markets as an effort to increase the scale of GAF's chemical operations.

Many of Heyman's takeover attempts were to be funded with commercial borrowings from Chase Manhattan Bank and high yield debt from Drexel Burnham Lambert.

[8] Two years later, in 1991, Heyman spun off GAF's chemical business as a separate entity and sold 19.6% to the public, listing the company, renamed International Specialty Products Inc. ("ISP"), on the New York Stock Exchange.

Despite the mine being closed in 1975, asbestos litigation grew substantially, with GAF eventually paying out more than $1.5 billion in asbestos-related bodily injury claims.

[15][5][16] Heyman and his wife owned a large collection of modern art, including works by Alberto Giacometti, Jackson Pollock, Jeff Koons and Mark Rothko.