Seymour Stein (born 18 April 1942  ) is an entrepreneur in the music industry. His first job was (an intern at King Records in Cincinnati, Ohio, the Birthplace of Rock N' Roll) then he took on a clerk position for Billboard magazine in 1958. Stein is a Vice President of Warner Bros. Records and a co-founder of Sire Records.  
In 1966, Stein and record producer Richard Gottehrer founded Sire Productions, which led to the formation of Sire Records, the label under which he signed pioneer artists such as the Ramones and Talking Heads in 1975, the Pretenders in 1980 and Madonna in 1982. Other acts signed by Sire include The Replacements (band), Depeche Mode, The Smiths, The Cure, Ice-T, The Undertones and Echo & the Bunnymen.
Such was Stein's influence in signing and promoting the new wave genre of music that he is sometimes credited with coming up with the name as an alternative to the term punk, which he found derogative. The term had previously been used to refer to the French New Wave film movement of the 1960s.
Stein remains the President of Sire Records and is also Vice President of Warner Bros. Records with which he has had a marketing and distribution deal from 1976 to 1994 and again since April 2003. He was inducted into the Rock and Roll Hall of Fame on March 14, 2005, under the lifetime-achievement category. On June 9, 2016, Stein has been honored with the Richmond Hitmaker Award at the Songwriters Hall of Fame.
Stein is the subject of an eponymous song by the Scottish musical group Belle and Sebastian. He was the winner of a Lifetime Achievement Award at the International Dance Music Awards in 2010. Ice-T wrote about Stein in his autobiography, stating: "He's cut from that cloth of the old-time music executives like Clive Davis, but he's way more eccentric... Just a little more bizarre, a bit more avant-garde, more of an edgy cat." He wrote that Seymour Stein would never edit Ice-T's musical output but would sometimes express concerns (e.g. he was against homophobia in rap).
Stein was formerly married to the late music promoter and real estate executive Linda Stein ; together, the couple had two daughters before they divorced, on amicable terms, in the late 1970s. Stein has never remarried. One of his children is Mandy Stein.