Didn't Rebels also use some of Ralph McQuarrie's original designs?
Yeah, tons: Pretty much all of the environmental design of Lothal as well as a lot of the costume design for the citizenry is all taken from various McQuarrie paintings; The former from a combination of his Cloud City building designs for tESB, and the landscape with the signature "beehive" rock spires from his unused Sicemon paintings for RotJ (though IIRC he credits Nilo Rodis-Jamero for the initial sketch idea.) Interestingly; a good portion of this artwork wasn't even produced for the movies, but specially commissioned for the '
Illustrated Star Wars Universe'.
On top of that of course their particular rendition of Vader was heavily inspired by Ralph's work, Zeb's design comes from his early Wookiee sketches, his early designs of R2 & 3PO directly inspired both Chopper &
a protocol droid design that showed up a number of times (though the real credit there should go to Walter Schulze-Mittendorf of 'Metropolis' fame), and I think the Stormtrooper cadet helmet started off as one of Ralph's sketches for what became the Snowtrooper. Even Kanan's lightsaber hilt has certain elements from one of McQuarrie's pre-graflex sketches. That's all just off the top of my head, and of course is just the tip of the iceberg.
All that said; mostly what 'Rebels' took from McQuarrie was his overall style and aesthetic, which is a little bit softer in shape and colour pallet than how things ended up in the movies.
I will note however to be cautious about attributing certain designs to a specific artist. There was a lot of collaboration between them, including modifying and iterating each other's designs back and forth, from Cantwell to McQuarrie to Johnston, back to McQuarrie and then onto the team at the ILM model shop, John Mollo's costume department, Stuart Freeborn's make-up effects shop, Roger Christian's set builders, John Barry production design team, prop builders etc. etc.
Point being; some very iconic designs passed through a lot of hands before getting to their final form, and everyone there deserves credit. Trying to pin down "ownership" of a specific design can often be a futile endeavour.
Didn't Vader start off as a two dimensional henchman?
Pffft. Vader in the early drafts could only
wish he had two whole dimensions to his character!
