Kevin has also done three Doctor Who-themed sketches for me. He did a Silurian and Kandy Man (from "The Happiness Patrol") for me. The last time I saw Kevin was at Fan Expo Canada in Toronto in 2014. I had a copy of the Eleventh Doctor's new comic from Titan with a blank cover. He drew Matt Smith's Doctor, and he threw in a fez and a bowtie on the back cover. It was days before I noticed that.
One of my favorite webcomics was Ensign Sue Must Die! Set in the "rebooted" Star Trek universe, Ensign Mary Amethyst Star Enoby Aiko Archer Picard Janeway Sue annoyed the hell out of the Enterprise crew. She wound up dying, but it kicked off two more stories that took place in a ton of universes. You can start here.
HONORABLE MENTIONS: Kyle Baker (six sketches), Art Baltazar (three), Lee Bermejo (two, including this awesome sketch of Caitlin Fairchild from Gen13 as Supergirl), Reilly Brown (five), Sal Buscema (this Man-Ape sketch from 2002).