Samuel Irving Newhouse, Jr. (born November 8, 1927), nicknamed Si Newhouse, is the chairman and CEO of Advance Publications, which, among other interests, owns Condé Nast Publications, publisher of many marquee brands in the world of magazines such as Vogue, Vanity Fair, The New Yorker, and Portfolio. He is the son of Samuel Irving Newhouse, Sr., founder of Advance Publications. His grandson, S.I. Newhouse IV, appeared in the documentary Born Rich.

Newhouse attended the Horace Mann School in New York City. He is a billionaire with an estimated net worth of $7.5 billion, and he was ranked the 26th Richest American by Forbes Magazine in 2007.

Newhouse is known for philanthropy, and gave $15 million to Syracuse University, as well for being a notable art collector.