"Although Frusciante recently acquired a genuine Mellotron, sampling, modern synthesis, and programming are clearly not where his heart lies. "

This video is a demonstration by Paul Mccartney, showing the Mellotron, and how Beatles used to make Strawberry Fields Forever.

In this image, Lennon is using a Mellotron MkII.

“Today I was at Robert [Fripp]’s place recording the mellotron parts for my new album on his original sixties MK2 mellotron, famously the one used on the debut King Crimson album. Playing a real mellotron is quite an exhausting physical experience, but it sounds amazing….” says Steven Wilson, in this article, about playing Robert Fripp's Mellotron MkII.

On this website, it quotes Steve Wilson saying, "Today I was at Robert [Fripp]‘s place recording the mellotron parts for my new album on his original sixties MK2 mellotron, famously the one used on the debut King Crimson album. Playing a real mellotron is quite an exhausting physical experience, but it sounds amazing…."

the Mellotron MkII can be seen on the top left of this picture

Richard Wright used a Mellotron MkII, famously known as Pink Floyd's own instrument, as detailed in the Fika publication.

Banks can be seen playing the Mellotron MkII on "The Fountain of Salmacis" and "The Return of the Giant Hogweed" on this Belgian TV appearance of Genesis. The clearest shot is at 1:56.

Jones can be seen in this studio shot seated at a Mellotron Mk II.

Herbie Hancock played the Mellotron on the tune Hidden Shadows for the 1973 album Sextant, as stated in "Herbie Hancock’s Electronic Instrument Glossary" (2016-09 based on liner notes from 2013):

"Mellotron – This electro-mechanical polyphonic keyboard, released in the 1960s, is in a class all its own. This instrument uses the technology of a sampler and a piano and looks like an organ. A key pressed causes this instrument to read a piece of magnetic audio tape and play back a preset sample lasting eight seconds. This instrument is played by Herbie on the tune “Hidden Shadows” for the 1973 album Sextant."

Additional information from another source. Herbie Hancock's use of the Mellotron sounds is also detailed in this page dedicated to the instrument used in music albums: https://www.planetmellotron.com/revh1.htm#hancock

"[...] on Hornets, [...], only uses the Mellotron on one track. Hidden Shadows features more of those volume-pedalled and/or pitchbent strings, but adds flute chords to the mix, [...]"

At 6:33 of this mini-documentary featuring Washed Out, the musician can be seen playing a Mellotron MkII.

John Lennon's was used on Odyssey & Oracle, as mentioned in this February 2016 Sound on Sound article.

Another revelation to Rod Argent during the recording of Odessey & Oracle was that, for the first time, he managed to try out a Mellotron Mark II, which ended up being used on various tracks, not least the strident pop of the album’s opener, ‘Care Of Cell 44’.

“John Lennon had left his Mellotron in the studio and I used it,” he laughs. “I thought it was great. The thing is, I initially thought, Well what a great way of being able to put an orchestra onto something. But of course it’s very different to that and much more in a way because its own signature sound made it much less middle-of-the-road. The quality of it just being sampled on tape, the strange sort of overtones that gave to the sound, were a huge bonus really. They made it sound terrific.”