The blonde actress rose to fame as cheerleader Claire Bennett in the original Heroes series, a plucky teenager with a super power that meant she could never die.
Her character was a fan favourite with the catchphrase, 'Save the cheerleader, save the world', still the best-known quote from the show.
Heroes Reborn picks up the old storyline of people who discover supernatural abilities, but while some much-loved characters are returning, cheerleader Claire isn't one of them.
Appearing on Live with Kelly and Michael in the US, new mum Hayden - who currently stars in smash hit TV show Nashville - explained: "I loved that show and it was such a huge part of my life. It took me a long time to get out of a cheerleader outfit!
"But I love where I am right now and I love Nashville. I just feel like I'm in a different part of my life right now, but I love Heroes so much and I can't wait to see what they are doing. They have some of the old cast back and I hope the fans love it as they are so loyal."