The world of sitcoms has lost one of its most influential figures in the person of James Burrows. The director passed away Friday morning at the age of 85. Especially the stars of "Friends" are saying emotional goodbyes on Instagram to the man who once affectionately called them his "Kids". 15 episodes of the NBC hit series bore Burrows' signature, including the pilot episode and the majority of the first season.

"Papa Burrows": Aniston mourns a father figure

Jennifer Aniston (57), seen in "Friends" as Rachel Green, found perhaps the most personal words. She called him "Papa Burrows" and wrote that the hardest part was that he had spent a lifetime making people feel loved - and now it seemed impossible to fit all that love into a few paragraphs.

Burrows always called the ensemble his "Kids", Aniston recalled: "Where are the Kids?" or "Let's see if the Kids can nail the joke." He was a father figure to her, celebrating them and carrying them through the hardest times as well as the best. Most of all, he taught the "Kids" how important it was to love each other and stand up for one another. She misses his voice, his laughter, his brilliance.

Courteney Cox and her nickname "Cox-N-Hammer"

Courteney Cox (62), cast in the series as Monica Geller, also spoke up. "Jimmy B" always called her "Cox-N-Hammer" - why, she never understood, but because it was Jimmy Burrows, she simply accepted it. He took the ensemble under his wing and taught them everything they needed to know. He never sugarcoated anything and was always right.

How someone with so much talent and wisdom could be without a conceited ego remained a mystery to her, Cox continued. Burrows' only concern was making everything as good as possible. She will miss him very much, but his light will always shine on her.

Kudrow, Schwimmer and LeBlanc pay tribute

Lisa Kudrow (62), who became known as Phoebe Buffay, shared a behind-the-scenes photo of the two from the third and final season of "The Comeback", in which Burrows played himself. She simply wrote: "Thank you Jimmy. I mean, for everything ..."

David Schwimmer (59), seen in "Friends" as Ross Geller, also honored the deceased. Burrows brought out the best in every actor and made every series better than anyone had expected. For him too, Burrows was a father figure: loving, wise and demanding at the same time.

Matt LeBlanc (58), who played Joey Tribbiani, posted a selfie with Burrows. Words could not describe the impact he had, LeBlanc wrote. Burrows was a true icon on so many levels.

More than 1,000 episodes of TV history

James Burrows looked back on an extraordinary career. More than 1,000 episodes of some of the most famous sitcoms in television history are to his credit, including "Cheers", which he co-created, as well as "The Mary Tyler Moore Show", "3rd Rock from the Sun", "Frasier", "Two and a Half Men", "The Big Bang Theory", "2 Broke Girls", "Will & Grace" and "Mid-Century Modern".