Billie Eilish will unveil her new hairdo in front of a national TV audience when she serves as host and musical guest on this week's .The 19-year-old pop star appeared alongside star Kate McKinnon in a promo for the upcoming show, which also marks McKinnon's return for the first time this season after stepping away to film her Peacock series, .Eilish, wearing an oversized hoodie under a puffer vest, looks stunning as a new brunette.