Concept art by Houston Sharp (first three), Klaus Wittmann (next one), and Art Bully Productions (last two).
Check out all his artwork here.
Check out more from wfdrawings/Wietze Fopma here.
Mark makes custom figures most are similar in scale to X-Plus figures, they are sculpted from epoxy clay and painted with acrylics. He definitely does some awesome work check out some here and more of his work on Facebook.
Check out more of Larry's artwork here.
Check out all Ian's artwork on ArtStation here.
Check out Inosuke-0101's page here.