Ever since 1978, fans have been able to insert characters into the imaginative LEGO worlds they've built through minifigures, or minifigs, the toys which sport iconic cylindrical heads and hands with square bodies and legs. The fan-favorite toy's creator, Jens Nygaard Knudsen, has passed away in his native Denmark at the age of 78.Knudsen, who worked for the Danish toy company from 1968 to 2000, was a prolific designer for LEGO for decades, lauded by colleagues for his boundless creativity. The minifig has since become one of the most recognizable elements of the global LEGO brand, with the toys featuring interchangeable heads, legs and torsos to match different roles and franchises. LEGO has since posted a tribute to Knudsen's contributions to the company online.RELATED: Baby Yoda, Mandalorian & More Minifigs Accompany LEGO's Razor Crest Set

"Jens spent 32 years with the LEGO Group and made an impact few can match," said LEGO Chief Marketing Officer Julia Goldin in a written statement to People. "He was a true visionary whose ideas brought joy and inspiration to millions of builders around the world and we thank him for helping to create some of our most loved play themes such as LEGO Castle, LEGO Space and of course, the iconic LEGO minifigure.”

Diagnosed with ALS, Knudsen reportedly passed away on Wednesday, February 19, in a hospice facility in Hvide Sande, Denmark, from complications with the disease.

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