Depending on who you talk to, it is either Les Paul (who also came up with about a zillion other things, including "sound on sound" and multitrack recording), Merle Travis, or Rickenbacker (with their Hawaiian steel guitar).
Leo Fender introduced the "Broadcaster" (eventually renamed "Telecaster," after a trademark dispute) and of course, the "Stratocaster." But these were later on.
However, there's no dispute that Fender DID introduce the first Electric Bass Guitar.
Mark
Fender’s Broadcaster pre-dates the Gibson Les Paul by a number of years. It was the first commercially successful solid-body electric guitar.
1949: Fender Broadcaster
1952: Gibson Les Paul
1954: Fender Stratocaster