I loved the aliens of Jabba's Palace as a kid. That weird hodge-podge of alien designs was my favorite thing about Return of the Jedi. Back then, I thought of Klaatu as one of the "hero" aliens, i.e. an alien that was actively involved in the scenes, like the Gammorean Guard. That's not really the case though. He didn't do much of anything other than get pwned by Luke on the Sail Barge. Still, I remember Klaatu was featured in a lot of the merchandising so he's an important aspect of ROTJ to me.
You likely know the legend regarding this character's name by now. He, along with Barada and Nikto, were named after the famous line in Day the Earth Stood Still. Later, Expanded Universe sources renamed the character "Wooof", along with virtually every other background alien in the vintage line. Why the powers-that-be of the Expanded Universe went out of their way to screw up the names of Star Wars aliens by changing their original Kenner names is beyond me. I'll always think of this dude as Klaatu, no matter what they say.
Kenner's 1983 figure was awesome, with a great furry soft goods and a cool alien sculpt. I also dig the figure's dark brown/green coloration. The modern Klaatu (or, Wooof... whatever) maintains the original's cool furry loin cloth, but updates the figure in every other conceivable way. The sculpt and articulation are fantastic, certainly better than a second-tier background alien like Klaatu deserves (although I'm not complaining). Check out Klaatu, then and now, below!