I could be wrong (as usual), but I think the fella with the one syllable name was played by Jim Carey. This is a guess, though, tbh.
Can you believe I only learned which was Beavis and which was Butthead a few weeks ago? I saw a meme where a guy looked like Beavis and had to settle the mystery once and for all. I wondered which was which since they came out but never watched the show.