Belldandy is the first of the Relief Goddess Office goddesses that we are introduced to. She is very pretty, with golden/light brown hair and triangular markings underneath her kind, blue eyes. Her forehead bears one of the characteristic goddess marks. She uses mirrors as her link between our world and Heaven, as well as for teleportation means.
Urd
Urd is Belldandey's older sister, and she's the second Relief Goddess Office goddess we meet. In the anime, she is introduced in episode 2, and in the manga she appears in volume 2. She's introduced when she materializes from keiichi television, which tells us that her teleportation medium and link to Heaven is through TV sets. Urd has tanned skin and flowing, slightly curled, white hair. She has green eyes, and like the other goddesses, her face carries the goddess markings. In addition to acting as the system administrator for the Yggdrasil system back in Heaven, she's also the series' Cupid (love goddess). Urd is very good with magic potions, and has a special passion for sake. Oh, and she likes singing (karaoke and sake is a good mix :-).
Skuld
Skuld is the youngest of the three goddesses, and makes her first appearance in volume 5 of the manga, and episode 3 of the OVA series (Burning Hearts on the Road). She materializes out of the water in Keiichi's bathtub in the OVA, whereas in the manga, Urd is in the bath instead of Keiichi. Skuld has black hair and dark brown eyes. In addition to being the Yggdrasil system's debugger, Skuld is very good (?) at building all sorts of echanical inventions - most of them not functioning quite the way they should. Skuld is very found of ice cream (131's Ice Cream being her favorite) and she dislikes useless mecha.
Peorth
Peorth is the fourth, and the oldest goddess to appear. She made her appearance in middle of manga volume 11, and lasted till the end of manga volume 12. She has red/brown hair, deep brown eyes, and diamond - shaped markings on her forehead and cheeks. Her method of manifestation is through camera lenses. She likes Keiichi, romance comics and roses.
Morisato Keiichi
Keiichi is the rather short, somewhat shy, but kind NIT student who accidentally ends up living with Belldandey He's got wild, dark hair and brown eyes. He is also the star driver of NIT's Motor Cycle Club (NIT MCC). Oh, and he can't swim! Keiichi is also learning Fortran 77, by the way.
Morisato Megumi
Megumi is Keiichi's younger sister and also a student at NIT, like her brother. She's about the same height as Keiichi, and has average length dark hair and brown eyes. Megumi is the typical "younger sister" (all big brothers know what that means! ^_^;), but she is by no means a stereotype. Furthermore, she's a Mechanics Major at NIT, she's good with engines (under the supervision of Keiichi) and an excellent softball player.
Tamiya-sempai
Tamiya is one of Keiichi's sempai - senior student - at NIT, and the head of the NIT Motor Cycle Club. He's a large man with short black hair, small eyes and a big mouth (physically!). Tamiya takes the concept of perfecting engines to rather passionate extremes (check out the speech he makes to Keiichi in OAV 3!) and he has a habit of appointing Keiichi to be the driver of the NIT MCC's modified vehicles. Not always with the predicted end results...
Ootaki-sempai
Ootaki is Tamiya's best friend and also one of Keiichi's sempai. He's got long spiky white hair, wears assorted bolts and metal parts in a thick necklace and has a sparkplug attached to each of his ears. Furthermore, he wears a black leather jacket with a complete set of tools under it and he ALWAYS wears his round mirrorshades. He's afraid of dogs. Ootaki's girlfriend is Satoko Yamano - a freshman and Electronics Major who Belldaney and Keiichi helped him get together with (chapter 6, volume 1 of the manga).
Mishima Sayoko
Sayoko is very pretty, with long, black hair and brown eyes. She's the official "queen" of NIT, and every male student there has tried to get a date with her, including keiichi. When Belldandey arrives, her position as campus queen is threatened and her current goal in life appears to be to win Keiichi from Belldandy. More often than not, she gets help from Aoshima to realize her plans.
Aoshima Toshiyuki
Aoshima is a slick sleezeball usually seen hanging around with Sayoko helping her out with her plans to split up Belldandey and Keiichi. His reason for doing this is simple: he's nuts about Belldandy. In addition to helping out with Sayoko's plans, he's already made several (unsuccessful) attempts at winning Belldandy's heart. Aoshima has normal length hair, dark brown eyes and wears glasses. He's also the head and founder of Aoshima Formula - a rival club to NIT MCC.
Hasegawa Sora
Hasegawa is Keiichi's kohai. In OAV 4, she suggests employment possibilities to Keiichi, and delivers a note from him to Belldandey.She has short brown hair, brown eyes, and large, round glasses that give her the appearance of great studiousness. She is demure and obedient in the extreme, in a decidedly more muted way than Belldandy's frenzied urge to please. She wears incredibly short yet sexless miniskirts.
Mahler
Mahler is a demon from Niflheim (Nordic mythology's version of Hell) whose main pastime is to cause trouble for Keiichi and the goddesses. She's got blonde/white long hair which to a certain degree resembles Urd's, 2 thin diagonal stripes in a \/ shape on her forehead and double triangles under her eyes. Being evil, she has a preference for dark clothes with a slight touch of SM.
Banpei-kun RX
Banpei-kun RX is a robot that was originally constructed by Skuld to keep Mahler away from the temple where Keiichi and the goddesses live. The robot is constructed from several sphere-shaped parts and wears a large, wide-brimmed hat or helmet. Like Mahler, Banpei-kun is a character from the manga and has only had a small cameo appearance in the opening animation sequence of the anime.
Senbee
Senbee, who appears in volume 7 of the manga, is a genie which can cause bad luck, and he speaks like a stereotypical gaijin (i.e., in mixed Japanese/English). He's under Mahler's control, at least theoretically. Senbee is a parody of Hyakubee, the main character of Magical Super Asia, who is also cursed/blessed with the power of misfortune.