Big Bang Theory voice actress Carol Ann Susi - who played Howard's unseen mother - has died at the age of 62.
The Brooklyn-born actress passed away after a brief battle with cancer.
Susi made numerous screen appearances in various films and TV shows including Coyote Ugly, Becker, Grey's Anatomy and That '70s Show throughout her career.
Big Bang Theory producers Chuck Lorre, Steve Molaro and Bill Prady paid tribute to her in a statement, saying: "The Big Bang Theory family has lost a beloved member today with the passing of Carol Ann Susi, who hilariously and memorably voiced the role of Mrs Wolowitz.
"Unseen by viewers, the Mrs Wolowitz character became a bit of a mystery throughout the show's eight seasons. What was not a mystery, however, was Carol Ann's immense talent and comedic timing, which were on display during each unforgettable appearance.
"In addition to her talent, Carol Ann was a constant source of joy and kindness to all. Our thoughts and deepest condolences are with her family during this time, and we will miss her greatly."
It has yet to be made public how Susi's passing will be addressed on the hugely successful sitcom.
Here's Howard and his mother in a typical scene: