Alyson Hannigan (Lily Aldrin)
"How I Met Your Mother" has provided steady work for Hannigan following her run as Willow Rosenberg on "Buffy the Vampire Slayer" -- and has further ensured that she wouldn't forever be known as the girl who did that thing this one time at band camp. Hannigan will follow up her "HIMYM" run with a starring role on the CBS comedy pilot "More Time With Family," about a husband and father (Tom Papa) who's making a career change to spend more time with his family.
Neil Patrick Harris (Barney Stinson)
Doogie Who, sir? Between starring as America's favorite child doctor and taking on the role of consummate ladies' man Barney Stinson, Harris worked steadily but without much momentum, with the short-lived "Stark Raving Mad" being his longest-lasting project. Since "HIMYM," Harris has become a ubiquity, developing into a go-to awards host and providing voicework for the popular "Smurfs" movie franchise.
Josh Radnor (Ted Mosby)
Radnor has mostly focused on his "HIMYM" duties, though he has appeared in the films "Afternoon Delight" and "Liberal Arts."
Jason Segel (Marshall Eriksen)
Prior to "HIMYM," Segel was best known for "Freaks and Geeks," Undeclared" and "Slackers," three projects that epitomized the phrase "cult favorite." Segel's big-screen career has since exploded, with roles in "Knocked Up," "Forgetting Sarah Marshall," "This is 40" and "The Muppets," which he co-wrote as well as starred in.
Cristin Milioti (The Mother)
Milioti was primarily known for her stage work prior to coming aboard "How I Met Your Mother" last year, but that seems to be changing -- in addition to playing Jordan Belfort's first wife in the big-screen "The Wolf of Wall Street," she's landed a role in the upcoming NBC pilot "A to Z," from Rashida Jones and Will McCormack.
Cobie Smulders (Robin Scherbatsky)
Smulders has largely kept a low profile, appearing in the little-known "Avengers" movie franchise as well as "Captain America: The Winter Soldier."