Dancing With the Stars has added another celebrity to its upcoming lineup, and this one may be unfamiliar to an older audience.

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Hayes Grier, a popular star on the video app Vine, is set to put on his dancing shoes this fall. Hayes tweeted a video on Thursday of himself announcing that he will be part of the upcoming 21st season, which premieres in September.

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 The Vine star then tweeted a few more times to spread the word with the hashtag #hayesdwts.

At 15 years old, Hayes is the second youngest celebrity in history to participate in Dancing With the Stars. The youngest was The Hunger Games actress Willow Shields, who was 14 when she competed earlier this year in season 20.

Hayes joins the following previously announced celebrities for season 21: Bindi Irwin, Victor Espinoza and Nick Carter. Other prominent stars expected to be in the cast are Paula Deen and Chaka Khan, though neither has been officially confirmed by Dancing With the Stars.

The season 21 cast is gradually filling out, with the complete list of celebs and pros released on Wednesday, Sept. 2.

Pros that will return to partner next season with the celebs include Mark Ballas, Sharna Burgess, Witney Carson, Artem Chigvintsev, Val Chmerkovskiy, Allison Holker, Derek Hough, Peta Murgatroyd and Karina Smirnoff.

Since there were only nine pros announced, it is expected that more will be announced on or before Sept. 2.

Dancing With the Stars season 21 premieres Monday, Sept. 14 at 8 p.m. ET/PT on ABC.

Tags: Dancing with the Stars Reality TV ABC