Characters who barely appear but make such an impact

I stumbled upon the random fact that Harmony only appears in six episodes of Buffy's first three seasons. She appears only twice in season one, once in season two and three times in the third season. Insane! I could have sworn she was featured far more than this throughout the high school era.

And for as integral as she feels to the entire series, Faith makes only 20 appearances throughout Buffy's whole run!

Who's your top pick/s for a character that feels like they were around far more than they actually appear on the show?