"We have chosen to separate. We are sorry for any pain this causes family and friends," the couple said in a statement issued exclusively to People. "The enthusiasm we have expressed for each other's lives, spirits and careers is real -- we have been each other's cheerleader and friend during the past six years and continue to be so now and in the future."
Fischer thanked her fans for their support on her MySpace page and asked people not to try to make either her or Gunn feel better by trashing the other in a post.
"Please don't -- we still have the utmost respect for one another, and we'd have to delete you," wrote the 33-year-old actress who plays receptionist Pam Beesly on "The Office."
Fischer and her 41-year-old husband were originally introduced by Gunn's brother, "Gilmore Girls" actor Sean Gunn, and later worked together on the film "Slither,” which James Gunn wrote and directed.
The Emmy Award-nominated actress made headlines last spring when she injured her back at an NBC party.