He has black hair, and blue eyes and walks with a swagger. He is often seen with a cigarette, lit or not. Danny's hair is done up in an elephant trunk and he's almost always seen with his leather jacket, the only exception being towards the end of the play where he changes into a more sporty look to impress Sandy.
Danny has a stereotypical macho personality. During the summer when he met Sandy she claimed him to be gentle and sweet, however, once reunited with him in school she calls him "a fake and a phony", for he was trying to act cool in front of his friends by acting like he doesn't know her. He shows himself to be very image-conscious, only acting on his true feelings towards the end of the play. Danny is quite perverted and a show-off, claiming he and Sandy had sex during the events of Summer Lovin', which is a lie. This is also further proven in the scene in which Danny tried to have sex with her while watching a movie outdoors. Despite all of this he is shown to be a very loyal friend (especially towards Kenickie) and of good nature, as he tries to act on his feelings during the end of the play instead of playing the macho like he previously did.
He is the leader of the T-Birds. He has an on again / off-again girlfriend named Sandy Olsen that he claimed he saved from drowning over the summer; However in Summer Lovin', he was just showing off and embellishing a lot in front of fellow T-Birds. Sandy probably just got knocked off balance by a wave washing up on the shore and he helped her up. He told a raunchy, embellished version; Sandy told a more accurate, sweeter version "He showed off, splashing around."