A multi-neck guitar is a guitar that has multiple fingerboard necks. They exist in both electric and acoustic versions. Examples of multi-neck guitars and lutes go back at least to the Renaissance.
A Gibson EDS-1275 double neck guitar, with 12 and 6-string neck.
Mike Rutherford of Genesis, circa 1980, playing his custom Shergold guitar in its twelve-string/bass double-necked configuration
Chris Squire of Yes (2003) playing Wal triple-neck bass consists of 3 double-course guitar, fretted and fretless 4-string basses.
The Gibson EDS-1275 is a double neck Gibson electric guitar introduced in 1963 and still in production. Popularized and raised to iconic status by musicians such as John McLaughlin and Jimmy Page, it was called "the coolest guitar in rock."
Image: Stills Stephen 1983