Second Banana

Second Banana is a term that has been around since at least the days of Vaudeville that means "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. (And even as its show business usage dwindles, it's moved out into the wider meme pool to mean any person working in a subordinate role to another.

In terms of characters, it is most often the sidekick, best friend, or co-worker of the protagonist.

Live Action TV

 * Art Carney was Second Banana to Jackie Gleason in The Honeymooners.
 * In The Andy Griffith Show, and later in Mayberry RFD, Don Knotts was the second banana.
 * Neil Patrick Harris's Barney Stinson is the second banana on How I Met Your Mother.
 * Vivian Vance was usually Lucille Ball's second banana in I Love Lucy and The Lucy-Desi Comedy Hour.

Video Games

 * Luigi from the Super Mario Brothers games. Brawl in the Family got a joke out it.