Jeffrey Thomas Thacher (born December 23, 1967) is an American musician, best known as a member of the vocal group Rockapella.

Thacher was a 1990 graduate of Berklee College of Music's Music Production & Engineering program, and afterward spent several years in television & radio production when not performing[1][2] In 1991 Thacher performed as a tenor in Five O'Clock Shadow, when Rockapella was looking to add human-made drum sounds to their live shows.

As the mid-1990s progressed, the terms "organic" and "imitative" began to be used to describe contrasting a cappella vocal percussion styles, with Thacher as the most prominent progenitor of the "organic" approach, combining blatantly literal replication of drums with sounds that didn't seek to duplicate, but rather fill the role of a drum or percussive instrument.

The technique allowed intentional throat grunting sounds to be heard more effectively in live shows and on recordings (1997).

[1] He became the first such artist to be professionally endorsed by a guitar pickup company (Seymour Duncan, from 1998 to present, now D-TAR).