Story highlights Kate O'Mara played Caress, Alexis' sister, on "Dynasty"

O'Mara was frequent performer on UK television, often in soaps

Actress was also on "Doctor Who" as Doctor enemy the Rani

"We had great fun on Dynasty," tweeted her co-star Joan Collins

Kate O'Mara, the British actress best known for playing Joan Collins' sister Caress on the 1980s show "Dynasty," has died. She was 74.

O'Mara died at a nursing home in Sussex, UK, according to her agent, Phil Belfield.

"Kate O'Mara passed away peacefully today at a nursing home in Sussex after a short Illness," Belfield wrote in a statement. "She was a delight to know and an extraordinary woman and actress with a passion for Shakespeare and stage acting.

"A shining star has gone out and she will be sadly missed by all who have known and worked with her."

O'Mara was a mainstay of British television -- "as ubiquitous on British television screens as the test card," wrote the UK news site The Guardian -- who acted in such UK series as "The Brothers," "Howards Way" and "Crossroads." On the long-running "Doctor Who," she played the Rani, a renegade Time Lord who was an enemy of the time-traveling title character.

Colin Baker, one of the Doctors she acted with, tweeted his sadness . "Oh my goodness. Kate O'Mara is no longer with us. Sad sad news. A delightful, committed and talented lady and actress. We are the poorer."

To American audiences, however, she's probably best known as Cassandra "Caress" Morell, the glamorous, conniving sister of Joan Collins' equally conniving (and glamorous) Alexis Colby in "Dynasty," the ABC prime-time soap about feuding oil clans. Caress appeared midway through the show's 1981-1989 run to battle with Alexis, threatening to tell all in a book called "Sister Dearest." But Alexis, as she so often did, emerged victorious, purchasing the book's publisher and making sure the work never saw the light of day.

Collins remembered O'Mara on Twitter.

"Tragic news about Kate O Mara, we had great fun on Dynasty when she played my sister Caress who Alexis insisted on calling CASSIE ! RIP," she tweeted

O'Mara was a talented actress -- she kept her talent sharp with frequent stage appearances, including performances with the Royal Shakespeare Company -- but she was more recognized for her stunning looks. She was quick to acknowledge the role her beauty played in her career.

"Because my career has been based so much on my looks, when I finally pass my 'sell-by' date I think I'll probably pack it in," she once said in an interview, according to The Guardian.

However, she kept acting almost until her death. Just last fall, she could be seen in London's West End theater district performing in "An Evening with Kate O'Mara."

O'Mara, who came from a long line of performers, is survived by her sister, actress Belinda Carroll.