The climate activist's grandfather was an actor, voice artist and director, with a career that spanned over 75 years. Greta was in the UK at the time, where she met Malala Yousafzai.
Teenage climate activist Greta Thunberg took to social media on Tuesday to write a tribute for her grandfather, Olof Thunberg, who died at the age of 94. Thunberg was a Swedish actor and director, with a career spanning over 75 years.
"He was one of the nicest people that I ever met. We miss him terribly," Greta wrote on her Twitter and Instagram handles.
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Greta's younger sister, Beata Ernman, also posted a series of pictures of the veteran actor on Instagram with a caption that read, "Rest In Peace Grandpa."
Thunberg was a well-known face on stage in Sweden, starting his career soon after the end of World War II. He went on to act in several films and TV shows, and even direct some TV movies later on in his career.
While he gave some spectacular performances during the course of his career, it was his portrayal of organist Fredrik in the 1963 classic "Winter Light" that made him known in the international circuit.
Thunberg was also the voice behind the tiger Shere Khan in the Swedish version of Disney's "The Jungle Book" and its sequel.
Greta also spent some time with Malala Yousafzai on Tuesday at the University of Oxford in the UK, where the Pakistani Nobel laureate is studying.
Greta is set to attend a school strike in the country on Friday, but took some time to visit her "role model" Malala.
The 17-year-old has received international recognition, becoming probably the most recognizable climate activist in the world. She has been nominated for the Nobel Peace Prize for two consecutive years.
Malala received the Nobel Peace Prize in 2014 for her advocacy of women's education, two years after being shot in the head by the Taliban on her way back from school.
see/msh (dpa, Reuters)