Hi, please take a break from changing and adding performer credits. We like use sources to help confirm added info on the Wiki, and specifically in the case of identifying who performed what character, we add when it can be supported by a reliable source (whereas user-generated sources like YouTube and IMDb are not), or if a consensus is reached from a discussion. I highly recommend reading Muppet Wiki:Identifying Voices for more on this topic, and next time, please discuss on our forum before making changes. Thanks!
You're still changing performer credits on Episode 223: John Cleese. The Marvin you're referring to (the green Whatnot with glasses seen during At the Dance) is in fact Dave Goelz, and not Richard Hunt who performs a waiter in the same sketch, so the note is correct. If you want to postulate voice identifications and discuss with other users on our Forum, you can, but do not make any more related changes without at least discussing it first.
If you continue to add or change content without sourcing or communicating, you will likely be blocked from editing. Please leave a reply here so I know you've been reading these messages and understand what's being discussed.
Hi, Jonathan already warned you twice, and another admin had to revert many of your continued changes to performer credits. This is the last warning.
Do not make any changes without either explanation or, preferably, asking first. See Astoria and the talk page, we don't know who the performer is (it's not Whitmire). For Elmo, Nelson is included in a footnote since he played the monster puppet that *later* became Elmo (not the Elmo character) once or twice. And so forth.