Danny Mahealani was Jackson's best friend, the former boyfriend of the werewolf Ethan and is good friends with Stiles and Scott. His last name is Hawaiian for "full moon". He is one of the Beacon Hills High in-crowd and is openly gay. He is the goalie on the lacrosse team and also plays trumpet in the school band. Danny often tries to calm Jackson down when he is angry or frustrated. He also seems to have befriended Scott and Stiles in indirect ways. Stiles often wonders aloud if Danny finds him attractive, comments which Danny usually ignores, but once returns by snidely offering to sleep with Stiles.
In Season 2, Danny helps Jackson recover lost footage from his camera which Jackson shot for his first full moon transformation with Jackson's instruction not to watch the footage. He manages to do so with help from Matt Daehler whom he is attracted to. He doesn't act on his attraction because Matt's into Allison. In "Frenemy", he is shown to be depressed over his break-up with his ex-boyfriend, Damon at the gay club, Jungle. Presumably, because the Kanima's Master wanted to remove any evidence, Danny is attacked at the club, but is only paralyzed by the Kanima and the footage Danny recovered from Jackson's video has vanished. In the episode, "Battlefield", he is warned by Jackson to not get anywhere near him during the lacrosse finals game, most likely because Jackson is somehow aware he is the Kanima and is killing people.

In Season 3, Danny develops an interest in Ethan, one of the Alpha pack,[9] unaware that Ethan was originally using him to get leverage on Scott. Although Danny doesn't realize it, his relationship with Ethan softens the werewolf to the point where he is willing to change for the better going as far as meeting Scott and Stiles halfway. In episode 7 "Currents", Danny is lethally poisoned with mistletoe by the Darach and his lung collapses. Ethan, obviously excessively worried about Danny, helps him to the hospital, where Melissa McCall saves his life using a needle thoracostomy. It's revealed Danny was targeted by the Darach because he did a project on telluric currents which were placed on the locations of where the Darach was sacrificing his victims. Despite the fact that Ethan was only supposed to manipulate Danny's feelings to gain information, as Aiden had been assigned to do with Lydia, he eventually fell in love with Danny and is shown to have several tender moments with him. However, in season 3B, after their separation and Ethan and Aiden later decide to re-enroll in high school, Danny is shown making out with Damon, his ex, which Ethan is clearly upset about, to Aiden's amusement. In "Illuminated", because of the power outage, Danny wants to hold a black light party, but is cut down. Ethan and Aiden help him out by acquiring a power generator and letting him use Derek's loft for the party. Danny is very pleased with the results and bonds with Ethan again. In "Letharia Vulpina", Danny is seen with the cross country team on the track where traps are laid by the Nogitsune and Ethan tackles him to protect him and says he missed Danny and proceeds to make out with him. When Coach Finstock is shot by an arrow triggered by a trip wire, Danny looks on while Ethan stays protectively beside him. In "The Divine Move", Ethan comes to break up with Danny, saying he can't stay after Aiden's death. Danny lets Ethan down gently, breaking up with him instead, saying that while he likes Ethan, he can't date a werewolf - Danny was aware of the supernatural all along, to Ethan's surprise. Ethan gives Danny a kiss goodbye. Show creator Jeff Davis reveals Danny graduated early during junior year.