It is a truth universally acknowledged, that a single woman starring in a romantic comedy, must be in want of a man — and have a best friend (or sister) on hand to crack wise and provide emotional support while she deals with him. Many actresses have proven to be experts at playing this part: the voice of reason, the hatcher of plots, the teller of sex jokes. There’s Christina Applegate, who has made a career of being a sassy best gal pal to Cameron Diaz, Gwyneth Paltrow, and, this week, Drew Barrymore; there’s Judy Greer, who quirkily guided Katherine Heigl through her romantic crisis, and will shortly do the same for Anne Hathaway; there’s Krysten Ritter, who sweetly counseled Isla Fisher, and will soon assist a vampire Alicia Silverstone; and that’s just to name a few actresses who regularly deploy best-friend capabilities in romantic comedies. So how do you choose the perfectly replaceable, yet ideally scene-stealing best friend that’s right for your movie? Why, use this handy flowchart to find out!