Please don't change performers without starting a conversation about it with the rest of the editing community at Special:Forum, as you did on Fred (monster). It's possible you're correcting an error, but it's also possible that you've misidentified a voice that has been established in the history of an article. To be sure, we can't trust a single set of ears when it comes to voice chasing, so a consensus should be reached. Thanks for understanding.
Hi, and thanks for your addition to the Grover article. I had to revert the change for now as that information doesn't fit in the infobox. Please see the text of the article for more on that topic. Thanks!