Simon Hugh Zentner (June 13, 1917 in New York City, United States – January 31, 2000 in Las Vegas, Nevada) was an American trombonist and jazz big-band leader.

Zentner played in the bands of Les Brown, Harry James, and Jimmy Dorsey in the 1940s, then moved to Los Angeles, where he worked as a studio musician. He also landed a job with MGM from 1949 to the mid-50s, and was involved in the music for films such as Singin' in the Rain and A Star Is Born.

The Zentner band began recording for Liberty Records in 1959, recording numerous successful pop/jazz albums during the 1960s and touring steadily with a large outfit. Zentner was a tireless promoter and claimed to have played 178 consecutive one-night performances when the band was at its peak. His ensemble was voted "Best Big Band" for 13 straight years by Down Beat, and Zentner himself was voted Best Trombonist in Playboy Jazz Readers' Poll. In 1962, his album Up a Lazy River (Big Band Plays the Big Hits, Vol. 2) (arranged by Bob Florence) won a Grammy Award for Best Pop Instrumental Performance.

Zentner's success was thoroughly unusual; he had a thriving big band going at a time when big band music was, for the most part, on the wane. He suffered from leukemia late in life, though he continued performing into 1999; he died of the disease in early 2000.