Diane's Duane's novel-original characters also appear in her several "Star Trek" comics and the text-based computer game, "The Kobayashi Alternative".

Duane Trek by
Ian McLean, on Flickr
Above: Naraht the horta; Harb Tanzer, Chief of Recreation; Nurse Lia Burke; linguist Janíce Kerasus; and Doctor Tom Krejci (DC Comics TOS Series I: the "Double Blind" two-parter, #24-25, and "The Last Word", #28). All of these characters have appeared in Diane Duane "Star Trek" novels, and most also in the old, text-based, computer game, "The Kobayashi Alternative". Other Duane novel/game characters who get mentioned by name in "The Last Word" comic include Athende (the tentacled Sulamid), and Avoca.
In the omnibus of her first four "Rihannsu" novels, "The Bloodwing Voyages", Diane Duane revealed that the transporter technician, Theresa Renner, is named for her former housemate.
Harb's hair is miscoloured in the comic; it should be
silver/white. When I was customising a Harb action figure, I emailed to clarify with Diane as to what mustache she had imagined for Harb and she said that it should be similar in style to Scotty's.
I ended up adapting a spare "Gilligan's Island" Skipper head for my Harb.
Trek customs... by me by
Ian McLean, on Flickr