'Peppa Pig' Star David Graham Dead at 99

Renowned voice actor David Graham, who is best known for voicing Grandpa Pig on the beloved children's series "Peppa Pig," has died ... a former colleague confirmed.

The X account for Gerry Anderson, the creator of "Thunderbirds" -- in which Graham voiced various characters for the British science fiction series and its spinoffs -- broke the sad news to fans on Friday.

The message read ... "We're incredibly sad to confirm the passing of the legendary David Graham. The voice [of] Parker, Gordon Tracy, Brains and so many more. David was always a wonderful friend to us here at Anderson Entertainment. We will miss you dearly, David. Our thoughts are with David's friends and family."

The update did not note a cause of death for Graham. Gerry Anderson pre-deceased Graham in 2012, when he died at the age of 83 after a battle with dementia.

As for Graham, he was notably the only original "Thunderbirds" cast member to return for the 2015 reboot, titled "Thunderbirds Are Go!"

In addition to his work on "Peppa Pig" and "Thunderbirds," fans of "Doctor Who" will likely recognize Graham's iconic sound ... as he voiced the villainous Daleks on the long-running sci-fi series.

He was 99 years old.