John Frusciante uses a Fender Bass VI, according to this "Premier Guitar" interview:

"'Is one of those subtle guitar parts on “Fanfare” a bass?'

"I play a Fender Bass VI on that song—and a Strat, I think. The Bass VI is a bass that feels like a guitar. The strings aren’t wide apart, and it has a guitar-like sound compared to a bass. You can play open chords—anything you can play on guitar sounds nice on it."

At 2:23 and throughout this video you can see Jack playing a Fender Bass VI.

“David has a 1963 Fender Bass VI. It’s strung relatively light for a baritone. But it’s still a 30-inch scale, so I thought I’d get him a new one made. I wanted it to be more like a guitar, shorter scale, but it also had to have a vibrato on it. I talked to Fender, and they made two."

This website states that Slash used a 1962 Fender Bass VI for a small amount of studio work over his career. This includes, but is possibly not limited to:

Solo, Ft. Myles Kennedy & The Conspirators: "Dirty Girl" (World on Fire) 2014

Slash's Snakepit: "Been There Lately" (Ain't Life Grand) 2000

Guns 'n' Roses: "Right Next Door to Hell" (Use Your Illusion I) 1991

As well, in photo #10 of the page, we can see a Red 1965 Fender IV Bass.

Studio guitars

"Guitar is the best form of self-expression I know. Everything else, and I'm just sort of tripping around, trying to figure my way through life." (-Slash)

For studio sessions, Slash almost exclusively uses a 1959 Les Paul Standard replica made by Kris Derrig. It is with this instrument that he recorded almost all parts of Guns N' Roses, Slash's Snakepit, Velvet Revolver and solo albums. However, when he wants a specific sound for some parts, he sometimes plays with other guitars such as Flying V, Explorer, Stratocaster or Telecaster.

• Gibson Les Paul Standard 1959 replica (main studio guitar used on almost every song/album)

• Gibson Les Paul Goldtop 1956 (rhythm) (Estranged / Fall To Pieces / You Got No Right)

• Gibson Slash Les Paul Appetite (rhythm) (Standing In The Sun / Halo / Bad Rain)

• Gibson Flying V 1959 (lead) (Live And Let Die / Knockin' On Heaven's Door)

• Gibson Explorer 1958 (lead) (Locomotive)

• Gibson SG 1961 (My Michelle)

• Gibson ES-335 1967 (rhythm) (Back To The Moment / Loving The Alien)

• Gibson ES-135 (rhythm) (Wicked Stone / Stone Blind / Beneath The Savage Sun)

• Gibson Les Paul Junior (slide) (30 Years To Life)

• Gibson Les Paul 12-strings 1990 (rhythm) (You Got No Right / The Dissident)

• B.C. Rich Mockingbird (lead) (You Could Be Mine / The Truth / The Alien / Headspace)

• B.C. Rich Warlock (Reckless Life / Nice Boys / Move To The City / Mama Kin)

• Travis Bean 1000 (slide) (Bad Obsession / The Garden / Beggars And Hangers-On / Shine / Rusted Heroes)

• Fender Stratocaster 1965 (lead) (Yesterdays / So Fine / What Do You Want To Be / Back And Forth Again / Sucker Train Blues / Gravedancer)

• Fender Telecaster 1956 (rhythm) (Sucker Train Blues)

• Fender Bass 6-strings 1962 (rhythm) (Right Next Door To Hell / Been There Lately / Dirty Girl)

• Gretsch 6120 Setzer (rhythm) (The Last Fight / Gravedancer)

• Guild AJF30 (Patience / Used To Love Her / You're Crazy / One In A Million)

• Martin D-18 (rhythm) (Not For Me)

• Music Man Baritone (rhythm) (We Will Roam)

Clapton's Bass VI can be seen behind him at 2:00 of this clip.

in this picture you see stevie using it

Auerbach states that he and Patrick Carney used a Fender Bass VI while recording their album, at 0:40 in this video.

George Harrison can be seen playing the Fender Bass VI most clearly at 5:50 in this TV performance of "Hey Jude."

Johnny mentions his Fender Bass VI on his website:

"My Fender Bass Six, or Baritone Guitar. I used it on “Helpline Operator” by The The. It’s tuned to A D G B E A.”Gary Jarman played it on Stick To Yr Guns from Ignore The Ignorant by The Cribs and Ryan Jarman played it on Save Your Secrets.”

John Played this bass for the "Get Back" sessions, as it shows on the "Beatles Get Back" doccumentary, also is seen on the "Let it be" music video

According to a compiled list of stringed instruments used on "The Fragile" as detailed by NinWiki, Trent Reznor utilized a Fender Bass VI.

Jim Root features a Fender Bass VI in his collection, as shown in a post on his Instagram account.