For nine unforgettable seasons, How I Met Your Mother delivered humor, heart, and a few too many blue French horns. But behind the laughter and legen—wait for it—dary moments, the cast and crew had their own incredible stories. From real-life romances to near-miss casting decisions, here are 35 fascinating behind-the-scenes facts that will make you see this sitcom in a whole new light.
1. Robin Was Never the Mother — From Day One
Creators Craig Thomas and Carter Bays made it clear from the pilot that Robin wouldn’t be “the mother,” dodging comparisons to Friends’ Ross and Rachel. They wanted Ted and Robin’s story to be about a deep, sometimes romantic friendship that was simply never destined to work out.
2. Barney and Robin’s Love Story Started with Neil Patrick Harris
Neil pitched the idea himself, sneaking in extra glances and subtle chemistry during scenes until the writers noticed. Cobie Smulders was initially against it but grew to love the pairing once it developed.
3. Britney Spears Saved the Show
Britney guest-starred in Season 3 as Abby, Stella’s receptionist, bringing a massive ratings boost that secured the show’s future after the 2007–2008 writers’ strike.
4. A Real Proposal Happened on Set
During the Season 2 finale, real-life couple Jana Rugan and Timothy Russo got engaged in the middle of filming — with the entire cast as witnesses.
5. Pregnant but Not on Screen
Alyson Hannigan and Cobie Smulders were both pregnant during Season 4, but their characters weren’t. Clever camera angles, props, and extra time at Robin’s news desk hid the bumps.
6. Lily’s First Pregnancy Was Real — Sort Of
When Alyson became pregnant again during Season 6, the writers decided to let Lily share in the joy, making it part of the storyline.
7. Jim Parsons Almost Played Barney
Before he was Sheldon Cooper, Parsons auditioned for Barney. The casting description called for a “big lug,” which he found hilarious — and admitted Neil was the better fit.
8. Neil Patrick Harris Wasn’t the Original Type for Barney
Barney was written as a heavyset, dark-haired man in his late 30s, but Neil won the role after a high-energy audition that included a dive roll from the pilot’s laser tag scene.
9. Robin Could Have Been Jennifer Love Hewitt
Hewitt turned down the role to star in The Ghost Whisperer, leaving the door open for Cobie Smulders.
10. Jason Biggs Passed on Ted Mosby
The American Pie star said no to the role, later calling it one of his biggest career regrets.
11. The First Pitch Was Nothing Like HIMYM
Before HIMYM, Craig and Carter pitched a show about a disgraced Enron executive teaching at an inner-city school — but abandoned it for their real-life friendship stories.
12. Ted and Marshall Were Based on the Creators
Ted mirrored Carter Bays, Marshall mirrored Craig Thomas, and Lily was inspired by Craig’s wife — who jokingly demanded Alyson Hannigan play her.
13. “Legen—Wait for It—Dary” Was Almost Cut
Initially, the writers didn’t want Barney to have a catchphrase. Thankfully, they changed their minds, making it one of the show’s most iconic lines.
14. Robin Sparkles Came from Canadian Pop Nostalgia
Inspired by early Alanis Morissette videos, the creators imagined a version of Robin who never grew past her cheesy teen pop days.
15. Alyson Hated Kissing Jason Segel
Because he smoked, Alyson said kissing him was like “kissing an ashtray.” A bet got him to quit — for about a year.
16. Robin Became Canadian Mid-Season 1
Cobie wasn’t originally playing a Canadian, but the writers decided it made her “exotic.”
17. Alyson Babysat Bob Saget’s Kids
Years before he voiced Future Ted, Saget had Alyson as his teenage babysitter.
18. Cobie’s Secret Pre-Scene Ritual with Josh Radnor
Before intimate scenes, she’d whisper something wildly inappropriate to Radnor right before “action,” leaving him flustered.
19. The Slap Bet Was Inspired by Real Life
Carter Bays had a running gag with a high school friend where they’d slap each other at random.
20. One “Slapsgiving” Slap Was Real
During filming, Jason Segel actually smacked Neil Patrick Harris for authenticity.
21. The Real MacLaren’s Pub Exists
Based on McGee’s Pub in NYC, the real bar even serves HIMYM-themed cocktails.
22. Jason Didn’t Read Lily’s Heartbreaking Line in Advance
To make Marshall’s grief real when he learns his father died, Jason avoided reading Alyson’s dialogue until the scene.
23. Scooter Was Played by Neil’s Husband
David Burtka portrayed Lily’s lovesick high school ex.
24. Robin’s Co-Anchor Was Alyson’s Husband
Alexis Denisof, Alyson’s real-life spouse, played Sandy Rivers.
25. Barney’s Coworker Was Cobie’s Husband
Taran Killam appeared as Gary Blauman.
26. Barney’s Fatherhood Ending Was Inspired by Neil’s Life
The writers knew Neil could channel genuine emotions from being a dad himself.
27. Neil Agreed Barney and Robin Should Split
He believed their relationship was never meant to last, and that his daughter was the one woman Barney couldn’t resist.
28. Cristin Milioti Auditioned Without Knowing She Was the Mother
Her audition sides were fake, and she had to sign strict NDAs.
29. Producers Worried Cristin Looked Too Much Like Alyson
Their similar features nearly lost her the role.
30. Her First Episode Had No Script for Her
To keep the secret, Cristin filmed without a script, surrounded only by production staff posing as extras.
31. The Ending Was Planned From the Start
Craig Thomas confirmed the controversial finale was always the intended conclusion.
32. Victoria Was the Backup Mother
If the show had ended early, Ted would have married Season 1’s baker.
33. Josh Radnor Knew the Twist Years in Advance
He learned in Season 1 and kept quiet until the end.
34. A Sweet Robin–Ted Scene Was Cut from the Finale
Josh wished it stayed in, as it hinted Robin had been thinking of Ted for years.
35. Ted’s Kids Filmed Their Ending in 2006
David Henrie and Lyndsy Fonseca shot their final scene eight years before the finale to preserve continuity.