She is best known for her roles as Jen Scotts in Power Rangers Time Force,[3] Ted Mosby's sister Heather in How I Met Your Mother, and Kendra Burke in Saving Grace.
Since then, she has worked in numerous films and television shows such as Supernatural, CSI: Miami, The Mentalist, Castle, Ghost Whisperer, Grey's Anatomy, and House.
She has appeared in commercials for Bank of America, TJ Maxx, Hyundai, Applebee's, Redfin, Tampax, Lean Cuisine, Honda, and Land Rover Discovery Sport.
In 2013, Cahill's projects included the short film The Ventriloquist, voice and motion-capture credits as Chloe "Karma" Lynch in Call of Duty: Black Ops II, and a guest role as Lena Gilbert in FOX's Sleepy Hollow.
[citation needed] In September 2016, Cahill married Welsh musician Paul Freeman in a ceremony on the Cote d'Azur, France.