Former EastEnders actress Gillian Taylforth said she is "shocked and saddened" by the death of her co-star Anna Wing.
Ms Taylforth, who played her character's daughter-in-law Kathy Beale, told Digital Spy: "What a lovely lady Anna was. It was so great to have worked with her.
"She used to say to me all the time that I should never forget her, so I always sent her birthday and Christmas cards every year.
"My thoughts go out to her family as she spoke about them often. She will be sadly missed".
An EastEnders spokesperson said they are "deeply saddened" to hear that actress Anna Wing has passed away.
They continued: "From the very first episode of EastEnders, Anna created one of the most iconic matriarchs in television history.
"Lou Beale is so entrenched in EastEnders history & without Anna, the Beale family would never have been the focal point it is today.
"Anna will be remembered fondly by everyone at EastEnders and our deepest sympathies are extended to her family and friends”.
June Brown, who plays EastEnders stalwart Dot Branning, said it was a "pleasure" to work with the "very generous" Anna Wing, who died aged 98.
Ms Brown, who first appeared in the soap in July 1985, said: "She was a very generous woman in many ways and an excellent actress who made a script her own, lifting the character off the page and made it quite different from what you'd have expected.
"Anna always thought well of everyone and she loved and enjoyed her children and grandchildren.
"I was very fond of her indeed and will remember Anna with great affection always".
Adam Woodyatt, who plays Ian Beale in EastEnders, has paid tribute to former cast member Anna Wing, who has died aged 98.
The actress played his grandmother Lou Beale in the soap.
In a statement posted to Twitter, he said: "So sad to hear that Anna Wing has passed away, she was a wonderful lady, very helpful and giving. I learned so much from her".
" I remember one episode...we had a seven page scene for the cliffhanger, Ian pouring his heart out to his Gran. It was the first time I had to cry on screen and I was terrified.
"Anna put me completely at ease. Sure enough the tears flowed from nowhere and it was the first time Julia's theme was used at the end of an episode.
"My thoughts are with her family and friends".
BAFTA said it is "deeply saddened" to hear that former EastEnders star Anna Wing has died:
We are deeply saddened to hear of the death of Anna Wing, who played Lou Beale in EastEnders: http://t.co/tEMlUsWVE3
Actress Anna Wing's most famous role was EastEnders' Lou Beale, the matriarch of the Beale and Fowler families.
In this classic clip from February 1985, Lou is unhappy that Pauline and Arthur Fowler have a baby on the way:
Former EastEnders actress Anna Wing, who played the sharp-tongued matriach Lou Beale, has died aged 98, her agent announced.
Ms Wing, who died on Sunday, appeared in the BBC1 soap for three years from when it began in 1985.
She formed a formidable on-screen partnership with fellow actress Gretchen Franklin, who played Ethel Skinner.