Glurp is the character played by Patrick Loller. He's an alien created for the Ships of the Northern Fleet tv show adaption and appeared as part of the main cast in most of the seasons, despite not being present in the books at all.
Glurp is a Wargobbler, a species with face tentacles and could change size. Patrick revealed that the effect was done entirely by prosthetics, robotic face tentacles, and camera angles.
Glurp often repeated his catchphrase "Swiggity swaggity, lets blow up gravity" and, in the final season, did exactly that using The Gravity Invalidator.
In order to produce the signature chaotic wave of Glurp’s face tentacles, 27 Kevlar threads were connected to the tentacles and to the clothing of the actor opposite Loller in the scene they were in. There were two different sets of prosthetics depending on the scenes that needed to be filmed. The “Crew” set has threads that could be attached to any actor, but this was a time consuming process. The “Annie” set of prosthetics was permanently affixed to a coat Annie frequently wore. This saved production time due to how many scenes Loller and Osbourn appeared in together. While the threads provided wave and lift to the tentacles, each tentacle also had between three to five constantly rotating servos that provided additional movement to the beard. In seasons one and two, the servos all operated on watch batteries that had to be replaced every four episodes in an extremely time consuming process. A redesign was commissioned after 70% of the servos failed at the beginning of shooting a Glurp intensive day. The new prosthetics were powered by lithium ion batteries that could be recharged via inductive charging. It’s estimated that over the course of the series run, this change saved production somewhere in the neighborhood of $70-80,000.