The 69-year-old actress has confirmed that she will bow out of her role as Albert Square's iconic Pat Evans later this year. St Clements said that leaving the BBC soap would be like "a bereavement".
Barbara Windsor, who departed the show last year, led the praise: "Pam St Clement created a truly iconic character in Pat. I was privileged enough to be a part of her journey, as Peggy and Pat fought, laughed and cried together.
"Pam will be greatly missed by the company and the viewers. I personally adore Pam and I can't wait to start having all those lunches we promised each other."
Patsy Palmer, who plays St Clement's on-screen granddaughter Bianca, said: "Pam St Clement is the most professional person I have ever worked with. She is an amazing actress who never fails to make me cry when we do scenes together.
"She will be missed by everyone at EastEnders but I feel really privileged that I have had this wonderful lady playing my nan for many years."
Co-star Charlie Brooks (Janine Malloy) added: "I'm devastated. Pam is one of my favourite people to work with and is also a close friend - I will miss her dearly."
Steve McFadden (Phil Mitchell) echoed the views of his colleagues, admitting that "EastEnders will be a strange place without Pam".
"I always loved the on-screen relationship between Pam St Clement and Mike Reid especially when they worked in the Queen Vic. This was one of the golden eras and I learnt a lot from them," he said.
"Pam is full of integrity and I have always admired her. She is never one to shy away from speaking her mind about the programme as she has so much love for the show. She is a lovely woman and I will truly miss her - as I am sure all the viewers will."
Ricky Butcher actor Sid Owen said: "I'm very sad to see Pam go, we've had a really close working relationship over the years. She's such an icon and I will miss her a great deal."
Executive producer Bryan Kirkwood has promised viewers that Pat will depart the soap in a "fitting storyline".
> 'Enders Pat: 'Losing co-stars was hard'