Sylvester L. “Pat" Weaver Jr. was an American radio advertising executive, who became president of NBC between 1953 and 1955.

He has been credited with reshaping commercial broadcasting's format and philosophy as radio gave way to television as America's dominant home entertainment.

At NBC, Weaver established many operating practices that became standard for network television. He introduced the practice of networks producing their own television programming, then selling advertising time during the broadcasts. Prior to that, ad agencies usually created each show for a particular client. Because commercial announcements could now more easily be sold to more than one company sponsor for each program, a single advertiser pulling out would not necessarily threaten a program.

His daughter is actress Sigourney Weaver.

Sylvester L. "Pat" Weaver was inducted into the Television Academy Hall of Fame in 1985.