Parlax is a Grundo in the employ of Dr. Sloth. He was originally in the Resistance, but betrayed them and his then friend, Gorix. Sloth then assigned Parlax the task of setting the Kreludan brothers Xarthab and Zorlix against each other. His identity was eventually discovered however, and he was briefly captured. Upon his escape, he returned to Sloth, escaping once more when his master was defeated.
In an old BTY (#503), it was implied he was also the unnamed Grundo who starred in Lost in Space Fungus. While BTY #715 implied Gorix and Parlax have somehow reconciled.
I was undercover as an orange Grundo when my ship was attacked by a giant Space Fungus. It happens. No matter; there is no prison that can hold me for long. It's only a matter of time before I can get back to my real work...
Gorix thinks he can escape, but I have a plan. It's simple enough, really... oh, did you think I was going to tell you? Nice try. You're working for the Resistance, aren't you?
That's one of us out there, and we never leave a man behind, do we? Now get out there and help get our boy home!
Well I was just trying to complete my mission when all of a sudden my nav system was affected by this...Space Fungus! Can you help to guide my ship back to safety?