John Frederick "Johnny" Gustafson (8 August 1942 – 12 September 2014) was an English bass guitar player and singer, who had a lengthy recording and live performance career.

Lead singer Brian Cassar left in 1960, and in January 1961 the remaining members returned as The Big Three.

When he was in The Big Three, the band often spent time with The Beatles, as they both played in The Cavern Club around the same time, and in 2007 even claimed to have played bass with the band on stage while bassist Paul McCartney sang "What'd I Say" on the microphone, and on one occasion played guitar with them for an entire set at the Grosvenor Ballroom in Wallasey as George Harrison was ill.[10] According to Gordon Giltrap, when he informed Gustafson of John Lennon's murder, he recalled selling Lennon one of his leather jackets for £5 in the early 1960s.

[12] For the rest of the 1960s, Gustafson found it hard finding new work, serving as a session player and a live performer and at one point being homeless.

Gustafson sang on the original recording for Jesus Christ Superstar as Simon Zealotes.

He made an appearance on Roger Glover's The Butterfly Ball and the Grasshopper's Feast album track, "Watch Out for the Bat", as a vocalist.

[16] Underwood formed a new Quatermass band in the 1990s without Gustafson, but he did contribute to two songs on their 1997 album "Long Road".

His last record with the band, Siren, included their only American top 40 hit single, "Love Is the Drug".

[2] Roxy Music front man Bryan Ferry later called Gustafson a "wonderful player", adding, "“Love Is the Drug” wouldn’t have been anything without the bass playing.