According Jeff Beck's tech, Stevie Prior, Beck uses an Octave Divider during his solo shows that's controlled in an offstage rack by Prior.

Neil Young's Mu-Tron Octave Divider is mentioned in this Guitar World interview:

"The slanted portion features five buttons: one for each of the four Whizzer presets, as well as a reverb kill. Across the top panel are switches for, variously, a Mu-Tron octave divider; an old, AC-powered MXR analog delay; a Boss Flanger in a “blue, cast-metal box”; and an Echoplex."

What's in the large console you use on stage? It looks very complex. "Well, actually it's not all that complex. It's a little rough to maintain. Things can get broken where it's shipped around. It's got a pair of Dynaflangers, a pair of MXR Flangers. It's got one input and four outputs – two dirty outputs and two clean outputs, all stereo. There's also two Big Muffs, Systec Harmonic Energizer – all these things are in pairs – Oberheim ECF, Eventide Harmonizer, MXR DBL, Mutron, DBX 162 compressors, Gain Brains, Kepexes, a Theremin and a Biphase. That's about it, and there's about 24 switches on the floor. I add to it every year. The Dynaflangers are on the newest thing. Oh yes, there's a Mutron Octivider and a DBX Boom Box. " - From the Guitar Player Magazine (May-June) in 1979, written down on the Frank Zappa Wiki "Wiki Jawaka"

In an Instagram post by Wes Borland, the Mu-Tron Octave Divider is visible among his gear, suggesting its use in his setup.

On the insert pic of this article a Mutron Octave divider can be seen on his pedalboard

Ace used this pedal for solos with Kiss, as described on a placard in an exhibition display that can be seen in this photo sourced from fansite Ace Frehley Les Paul’s “Ace Without A Les Paul” page. It is also mentioned in this March 1997 Vintage Guitar interview.

Exhibition card

ACE FREHLEY OCTAVE EFFECT USED DURING GUITAR SOLO WITH KISS

Vintage Guitar, March 1997, “Paul Stanley and Ace Frehley”

What kind of outboard gear are you using?

Very little. Right now, I’m using some DDL for the smoking guitar effect in the guitar solo. I used to use a Mutron Octave Divider, but now I find I like the Zoom better. It has reverb, compression, phasing you name it, it does it! I got it in a pawnshop. It’s one of the floor models, but I think I’m going to get the rackmount version for the tour so my roadie can control it. To me, the less effects I can get away with the better. I don’t understand why guitar players have a rack with 20 different things in it. Just plug a Les Paul into a Marshall, put everything on 10 and go for it!

In a photo from a Google search, Jerry Garcia's rack setup includes a Mu-Tron Octave Divider, positioned to the left of his Mu-Tron III. Garcia began using this pedal possibly in 1976, with confirmed usage from 1977 through the mid to late 1980s.

Talking about 2008 tour gear on georgelynch.com wordpress: "The OC-2 replaces the use of the MuTron octave divider that blew up on the road in 2007"

Used with Parliament and Funkadelic, as mentioned by Collins in this excerpt from a 1979 Guitar Player interview as transcribed TalkBass here and here from a reprint in Bass Heroes: Styles, Stories & Secrets of 30 Great Bass Players,

What kind of amps do you use in your setup?

The entire system is divided into three different parts - high, mid, and low. But we're not just talking about amplification, we're talking about the effects in each part. On my highs I use a Big Muff fuzz, a Mu-tron III [envelope-following filter], an MXR digital delay, a Morley Fuzz/Wah, a Morley Power Wah, and an Eventide Harmonizer. The Harmonizer sits in a case that looks like R2D2 from Star Wars. It looks just like a little robot, so I call it R2FunkU. There's a sign hanging on it that says, "Can I Play?" Inside of it, there's also a keyboard for the Harmonizer that enables me to preset harmonized intervals to what I'm playing. That way I can play a note and have a fifth or a third coming out at the same time.

All of that equipment just for the highs?

Right. For the mids, I have a Big Muff fuzz, a Mu-tron III, and an MXR digital delay. On the lows, I use a Mu-tron Octave Divider, two Roland Space Echos, a Big Muff fuzz, and a Mu-tron III. I keep all my effects in one box called the Space Case. The highs and mids each have an Alembic preamp, two Crown DC-300A amps, and four Cerwin-Vega speaker cabinets.

What's in each cabinet?

The cabinets used for the highs are called V-32s. They have two 12s, one midrange horn, and two tweeters. The midrange cabinets are basically the same, except there's one 15" speaker instead of two 12s. Those are called V-34s. On the bottom end are three Acoustic 370 heads and six Cerwin-Vega cabinets. Two have one 18" speaker and one 12", two more have an 18 and a 10, and two have one 18" and an 8.

Isn't that a lot of equipment for onstage?

I don't play it that loud. I've just got it there so that I don't have to strain the equipment and everybody can hear. As a matter of fact, the whole stage is set up like that. The guitar player, the keyboard player, everybody is set up like that so there is no real strain.

This was used during the Brown Album-era.

Cannibal Corpse records vocals and guitar solos at Mana Recording Studios with producer Erik Rutan. All footage was shot by the band.

As of 3:38 Pat can be seen using a Mu-Tron Octave Divider for lead tracks.

"Had this since high school."