Danny is portrayed by John Travolta in the 1978 film, by Aaron Tveit in the 2016 live performance, by Tom Parker in the 2017 UK touring production and by Nathan Parker in the 2017 play version (alongside his co-star and singer, Skye Hunt whom played Parker's love interest)
He has thick black hair, and blue eyes and walks with a swagger. He is often seen with a cigarette, lit or not. He's always seen wearing a T-shirt tucked into black jeans with a black belt, and black penny loafers with white or black socks. Danny's hair is done up in an Elephant's trunk - a popular `greaser' style of the 1950s - and he's almost always seen with his black leather jacket with the T-Birds logo on the back, the only exception being towards the end of the movie, at the carnival, when he earned his Letterman sweater in track, and wore it in order to impress Sandy, in turn shocking his fellow T-Birds, as the rest of the school. He went back to his T-Bird jacket when Sandy showed him her new female T-Bird look.
During summer vacation, he meets and falls deeply in love with Sandy, a beautiful and sweet girl from Australia at the beach. When it's time for her to return home to Australia, he believes their relationship is only the beginning, but he doesn't expect to see her again.
When the new school year started, Danny was genuinely happy and quite surprised to see Sandy again at his school, as her parents decided to not return to Australia, but because he was under pressure from his fellow T-Birds, he acted extremely rude and insensitive towards her, breaking Sandy's heart. She called him "a fake and a phony" and ran away crying. A few days later, Danny tried to apologize by explaining to Sandy that it was him, but it wasn't him. He was also jealous of Tom Chisum, the jock that Sandy was spending time with. After learning that Sandy liked jocks, he decided to become an athlete himself, and eventually decided on becoming a runner, determined to do anything to win her heart and be with her again.
Danny took Sandy to the school dance. Unfortunately, Cha Cha, a girl Danny once dated, got Danny to dance with her so they could win the dance contest. Danny tries to make it up to Sandy by taking her to a Drive-In Movie. He gives her his ring, but then tries make out with her in his car. Sandy fights back, getting out of the car and throwing Danny's ring in his face and runs off. Danny is heartbroken, believing the two of them belonged together.
The T-Birds and their rivals get together for a car race. After Kenickie bangs his head on his car door, Danny drives the car instead. Sandy watches the race and is thrilled when Danny won. She then asks Frenchie to help her, because she didn't feel happy.
At the school carnival, Danny shows up wearing a Letterman sweater in track, and tells his fellow T-Birds that they and Sandy mean a lot to him. Sandy shows up with a beauty makeover and shocks everyone - especially Danny. They pledge their love for each other, and drive away together in a Greased Lightning Car. The song was great !!!!