Lin-Manuel Miranda is an American actor, singer, songwriter, rapper, director, producer, and playwright (he keeps himself pretty busy!). Children may know him from the 2018 film Mary Poppins Returns, where he played Jack, a lamplighter (the new Dick Van Dyke character) Here he is – https://www.youtube.com/watch?v=oZ9WKQmcX2k. Adults may know him from Hamilton (which he starred in and wrote) or His Dark Materials on BBC which he was in before Christmas.