Josh Hutcherson and Haley Joel Osment pay tribute to co-star Glenne Headly

Josh Hutcherson and Haley Joel Osment have paid tribute to their Future Man co-star Glenne Headly following her death on Thursday (08Jun17).

Headly was in the middle of filming the series for online streaming service Hulu when she died at the age of 63. Her cause of death has not been announced, though sources told TMZ.com that she was being treated for blood clots last week (ends02Jun17).

In the comedy, which was set to premiere in the autumn, Headly played the mother of Hutcherson's character Josh Futterman, who must prevent the extinction of the human race after he is declared the key to defeating the imminent super-race invasion.

Following her death, her onscreen son wrote on Instagram, "I only knew the talented, empathetic, loving, beautiful Glenne Headly for a short time. She was powerful and strong and hilarious. Her eyes brought to life so many amazing characters over the years and her love brought to life a beautiful family.

"I'm gonna miss her presence, her smile, and the way she made me feel like her son before, between, and after they called action and cut. Grab onto those who make you feel loved. My heart is broken today and I can only imagine what those closest to her are going through."

Osment, who plays Dr. Stu Camillo, called her death "such a tragedy" and a "terrible shock" in an interview with TheWrap.com and confirmed she will not be replaced.

"They'll find a way to deal with that character's absence, but certainly for those of us who knew her from Season 1 and may have known her before, it's going to be a really sad, empty space on the show that she's not there anymore," he said.

Deadline reports Headly had filmed five episodes of the 13-episode first season and her character will be written out of the series, which is co-produced by Seth Rogen and Evan Goldberg.