Garfield, Squidward, Mr. Krabs, Hugh Neutron, Toph (AVATAR), Sportacus, Robbie Rotten (a good tribute), Snap (ChalkZone), Oswald the Octopus, Rabbids (Rabbids Invasion), Po or Kung Fu Panda (Kung Fu Panda: Legends of Awesomeness), Pablo (or any of The Backyardigans), 

Pingu (He appeared on Nick Jr for a few years, and on Nick in the UK, so he counts), 

I'm glad we're getting Wubbzy, Dora, Blue, and Jenny, so I don't have to ask for them. Wubbzy is my new main.