23rd Oct: It's time for the second TV Tropes Halloween Avatar Contest, theme: cute monsters! Details and voting here.
Second Banana is a term that has been around a really long time that meant "second billing" in an acting company. It's most often applied to comedians or comedies now; in such cases it's the supporting comedian, who may also be the Straight Man. The Second Banana may no longer actually get second billing. In terms of characters, it is most often the sidekick, best friend, or co-worker of the protagonist.