(written from a Production point of view)
Deep C-Zar (or Deep Czar ) was an alien character which appeared in a deleted scene from the alternate reality film Star Trek Beyond. In the scene, Deep C-Zar can be viewed in the background, meeting with Satine in a terminal at Starbase Yorktown.
The makeup for the character of Deep C-Zar was sculpted and painted in Vancouver, by Don Lanning and Daemon Cadman respectively.   The alien was a hybrid makeup which resulted from two sculpts coming together. (Information from Dae Cadman) Cadman recalled, "I had 2 shop days to complete that massive cowl, 2 faces and a set of arms (Holland Miller jumped in to do the arms for me) before it was shipped from Vancouver [....] The boss, Joel Harlow, gave me freedom and trust (quietly passing by my paint area to make sure I wasn't screwing anything up) to paint what I wanted."  In Dubai, Lenny MacDonald applied the makeup to the performer.  
As a result of the extraordinary amount of freedom that Joel Harlow afforded her in painting Deep C-Zar, Dae Cadman was extremely proud of how the alien's appearance turned out, with the character's back being her favorite part.   She remarked about the alien, "It's one of my favourite things I have ever painted [....] Wasn't too fond over how dark it ended up being upon application. Still loved it. The back was amazing." As such, Cadman was disappointed that Deep C-Zar didn't end up being in the film. (Information from Dae Cadman)
A two-page spread featuring Deep C-Zar was published in Prosthetics magazine (issue 5, p. 8-9). Overjoyed with the image, Dae Cadman explained, "I never thought I would see this little guy all put together and photographed so beautifully. I only had some shop photos which weren't too good."