The cast includes:
Ataru Moroboshi - His name means "to be hit by a star." Ataru is a lecherous, womanizing teenager who chases any cute girl that crosses his path. He accidentally proposes to Lum, and is turned off by her forceful advances. Instead he goes about trying to get back with his ex, Shinobu, when not chasing any cute girls he sees.
Lum - an alien princess from the Oni race, Lum wants to marry Ataru after he defeats her in a game of tag. She has to put up with chasing him and keeping him from other girls, though.
Shinobu - Ataru's violent ex, she tells Ataru she will marry him if he catches Lum. After Ataru accidentally proposes to Lum, Shinobu leaves him and her interests turn to Shotaru Mendou.
Mendou - rich, handsome, and surrounded by girls, Mendou is the envy of every boy and the desire of every girl, except the one he wants - Lum. If you take away Mendou's money and status, he is essentially Ataru.
Cherry/Sakurambo - Sakura's uncle, a short, somewhat disturbing and obnoxious little man. He always appears out of nowhere to speak of bad omens or to just be annoying.
Sakura - The niece of Cherry, Sakura is a powerful priestess as well as a high school nurse. All the boys love the beautiful Sakura, especially Ataru. She has absolutely no tolerance for their advances, though.
Jariten - Ten is Lum's little cousin. Lum is his guardian and he stays with her in the Moroboshi household. He flies and breathes fire, especially at Ataru, as they are huge rivals.
Benten, Oyuki, Ran - Three alien girls who are Lum's friends and former classmates. Benten is the aggressive, action-loving type; Oyuki is quiet, reserved, and intelligent; Ran is more of a rival. She hates Lum for all the little bad things that happened when they were little, and so she tries several times to get revenge.
Rei - Rei is Lum's ex-fiancee, a handsome alien male who turns into a giant tiger-striped cow. He is hungry 100% of the time and is always looking to be fed. Rei wants Lum back, but Ran wants Rei.
Onsen-mark - Ataru & company's annoying teacher. Loud, strict, bullheaded, and unintentionally funny.