Elderbug is a cool dude, let me tell you that. He's very kind to the Knight, and most of the time he's open to new travellers in Dirtmouth, or the city he resides in.  He's a very old bug, as his name might suggest, so middle age to senior voices would work. He has plenty of lines, but he isn't in every episode. You will need to know how to do effects, because a few of his lines require them. He should sound similar to this, just using actual words: https://youtu.be/uJmHIjG20O4 (profile art does not belong to me)