The founder of the streetwear company, Huf Worldwide, had been battling brain cancer for two years.
The name HUF just stuck with me as a sort of nickname amongst my friends," Hufnagel told Complex in 2012. "Once I turned pro, I started using it on product and clothing and it became what people recognized me by," he said.
The brand's first shop opened in San Francisco, but ultimately grew globally, with stores everywhere from Dallas, Texas to Tokyo, Japan.
"Made by skateboarders, for skateboarders, HUF represents not only a more refined and forward-thinking skateboard brand, but also any individual inspired by the vast array of countercultures that parallel skateboard mentality," the company says of its ethos
"Do not settle for the status quo. Go out and create your own future -- do it yourself, do it in style," urges the HUF Worldwide website.
Hufnagel described the brand's name as having been "born on the streets," telling Complex, "after I had been living and skating in San Francisco for a bit, I decided I wanted to open up a retail shop that would sort of fuse skateboarding with the sneaker and streetwear scenes."
In the tribute to its founder, the Huf Worldwide instagram post closed by saying that Hufnagel's "legacy will continue to live on at HUF. Today, tomorrow and forever. Rest in peace, Keith."
Hufnagel leaves behind his wife Mariellen and their two children.
In an instagram post in November, Hufnagel shared a shot of himself with his son, as the pair hold hands and skateboard together down an empty road.