Charlie Christian (Charles Henry) is the most well known of the early amplified jazz guitarists. He's considered by many to be the father of bebop guitar. Some go even as far as saying that Christian was a key figure in the development of bebop in general (in the early 1940's).
His new "sound" has supposedly influenced early bop recordings
by giants such as Dizzy Gillespie, Charlie Parker, Miles Davis and
Thelonious Monk. He was present at the legendary Minton's Playhouse jam
Christian was influenced mainly by horn players of his time. He wanted to make his guitar sound like a tenor saxophone! I believe that is why his improvisations blended so well in bands constituted primarily of winds.
described as a trailblazer his approach definitely influenced most
(all?) jazz guitarists that came after him. (Noticeably Wes Montgomery).
Christian used an amplified hollow body guitar. The first and main model was the Gibson ES-150
(mounted with a pickup near the neck).
amplification of an acoustic instrument was quite new at this time. The
most common "electric guitars" of this era were entirely electric
instruments (such as the "Frying Pan" played as a lap steel).
The ES-150 has been very much associated with Christian. The pickup, which
was the remarkable feature, was named after him later.