Danielle Spencer, the former child star who played sassy tattletale Dee Thomas on the 1970s sitcom “What’s Happening!!,” has died. She was 60.

Spencer died Monday after she “lost her battle with cancer,” her brother, jazz trumpeter Jeremy Pelt, announced on Instagram. Spencer had suffered other health issues — including a bleeding hematoma and a spinal cord injury — throughout her life.

“Many of you knew her as ‘Dee,’ but she was more than a child actress,” Pelt captioned the carousel of photos of his sister. “She was a friend, an auntie to my three children who adored her, she was a daughter — and in many ways, my mother’s best friend, she was a veterinarian, she was someone who always remained positive even during her darkest days fighting this disease.”

Pelt added: “She was MY sister and protector.”

Haywood Nelson, one of Spencer’s “What’s Happening!!” co-stars, told the Hollywood Reporter that “she suffered for a very long time but did it with a great deal of courage.”

Spencer was best known for her work on “What’s Happening!!,” which aired on ABC from 1976 to 1979. The Watts-set sitcom followed a trio of teens and also featured Ernest Thomas, Fred Berry, Mabel King and Shirley Hemphill. Spencer portrayed the meddling younger sister to Thomas’ Roger “Raj” Thomas. As Dee, Spencer garnered laughs for her deadpan delivery, dry humor and no-nonsense approach to family antics.

A constant thorn in her brother’s side, Spencer’s Dee also delivered memorable lines including “Ooh, I’m gonna tell Mama!”

During her time on “What’s Happening!!” in 1977, Spencer and her stepfather Tim Pelt were involved in a severe car accident. The crash killed Pelt and left Spencer with health complications that would affect her later in life. After the accident, Spencer was in a coma for three weeks and suffered broken bones in her leg, arm and pelvis, according to her website. In 2018, she underwent surgery for a bleeding hematoma that resulted from the crash.

Spencer had to use a wheelchair and underwent rehab to learn how to walk again in the early aughts. She was diagnosed with breast cancer in 2014 — she said her family has a history with breast cancer — and got a double mastectomy shortly after.

After “What’s Happening!!” ended in 1979, Spencer reprised her role for the syndicated sequel series “What’s Happening Now!,” which aired from 1985 to 1988. Spencer last appeared in a minor role on the long-running daytime drama “Days of Our Lives” in 2001. Her acting credits also include “The Brady Bunch Variety Hour” and the Jack Nicholson film “As Good as It Gets.”

After her acting career waned, Spencer shifted her focus to her studies, attending UC Davis and UCLA and eventually earning her doctorate in veterinary medicine from Tuskegee University in 1993, according to THR. She practiced in the Los Angeles area before moving to Richmond, Va., where she would return to TV in a different capacity.

She often appeared on CBS affiliate WTVR’s morning news programming, sharing her expertise on pet care. In 2014, she became the first child star inducted into Smithsonian’s National Museum of African American History & Culture, where her work as Dee Thomas became a permanent fixture.

Of the honor, she told BlackAmericaWeb.com in 2014, “I still can’t believe it.”

“That’s something people can look at for years to come, long after I’m gone.”

Spencer was born June 24, 1965 and raised in the Bronx. She also authored a memoir about her childhood stardom and pursued various business ventures including a candle line and clothing brand. In addition to her brother Jeremy, she is survived by her mother Cheryl.

The Associated Press contributed to this report.