The Worst

"He is not like of the worst, he is The Worst"  

The Worst is one of the many aliens unlocked in the Ben 10: Omniverse episode Outbreak. He was voiced by Yuri Lowenthal before being replaced by Dee Bradley Baker. His species comes from the same planet as Ball Weevil's species.  As his name implies, Ben considers this his worst transformation for lacking any combat abilities and being just a punching bag.

Appearance

The Worst is a roundish yellow blob with a large mouth and green eyes with eyebrows. He wears green underwear with a white band. He has three bumps on his head and arms as well as stubby feet with three black toes. He has a swirl pattern on his knee and the Omnitrix is located in his bellybutton.

Spidermonkey

"Why Grandma, What big trouble you have!" - Spidermonkey in What Are Little Girls Made Of? 

Spidermonkey in Ben 10: Omniverse

Spidermonkey is an Arachnichimp from the planet Aranhaschimmia. He is one of the original ten in Ben 10: Alien Force who makes his debut in What Are Little Girls Made Off? where he battled Verdona. He reappeared in the Ben 10: Ultimate Alien episode Fame where he battled Bivalvan before assuming his Ultimate form. Spidermonkey returned in the Ben 10: Omniverse episode The More Things Change: Part 1 where he battled Crabdozer, mostly trying to dodge and run away from the predator. Spidermonkey is voiced by Dee Bradley Baker.