Harem Nanny

"Hikaru/Kaoru: Who's "mommy"? Kyouya: From a club standpoint, I guess I am..."

- Ouran High School Host Club

Usually appears in the Harem genre, and keeps a look out for the major, non-daily disturbances in the household. Outside of that, the cast is on their own. This character is collected and cool as a cucumber, and isn't about to stress about every little thing. They have more fun amusing themselves with the cast's antics.

Notable for being probably the only character who will give you a simple straight answer for anything.

Usually older than the rest of the cast and never a romantic possibility (though occasional flirting isn't ruled out). Frequently has a sneaky streak that is not initially obvious and is thus an Unflappable Guardian.

Contrast Nerd Nanny.

Anime and Manga

 * Haruka in Love Hina
 * Tenchi's grandfather Yosho in Tenchi Muyo!
 * Though he most definitely would not give Tenchi a straight answer. And then third OVA introduced a whole bunch of these characters (Seto and Airi at the very least).
 * Shigure in Fruits Basket
 * Except for the straight answer part
 * Hatori and Hatsuharu fit also.
 * Ken Sanada in Parallel Trouble Adventure Dual
 * Miyabi in Ai Yori Aoshi
 * Akiko in Kanon
 * Kyoya of Ouran High School Host Club isn't the president of the club, but is considered the "mommy" of the group. Then again, he could just be considered a pimp. He is the one with all the answers as to what is going on, since Tamaki was too busy with ladies.
 * BC in Vandread
 * Chizuru, as well as most older characters in Mahou Sensei Negima (Albireo, Takemichi, Konoemon, ect.)
 * Subverted in the case of Takamichi, as while he would otherwise be a straight Harem Nanny, the heroine has a hard crush on him.
 * Nekonome-sensei fills this role in Rosario + Vampire, as she's both Tsukune's homeroom teacher and the sponsor of the Newspaper Club.
 * Her rather playful personality (while appropriate enough for a Catgirl) couldn't exactly be described as "cool as a cucumber", though.
 * Orie in Koi Koi 7.
 * Kasumi in Ranma ½
 * Miya in Sekirei, she is older than the rest of the cast and seem to enjoy teasing the protagonist calling him "Criminal"
 * A couple different characters play the role at different times in UFO Princess Valkyrie. Usually it's Kazuto, though occasionally Rika and Akina play the role as well.
 * Maria in Hayate the Combat Butler will occasionally have this role, depending on the episode. Granted, other times she's just another member of the harem, but otherwise she embodies the trope fairly straight.
 * Tsubame Ameyagi in Ai Kora is an interesting case. From the girls' perspective, she's the harem nanny—but to Hachibei, who's only interested in individual body parts, she and her legs are definitely part of the harem.

Live-Action TV

 * The Young Riders has Emma, the Pony Express station 'housemother' is pretty much this to the Pony Express riders. And she's handy with a shotgun, too, when outlaws coming calling.

Video Games

 * Fujimura Taiga in Fate/stay night is a partial fit for Harem Nanny. She's definitely not cool as a cucumber (in fact, she's the main comic relief), but she's the gatekeeper of Shirou's harem; each time another girl invades his house, Shirou's first problem is how to explain it to Taiga.
 * The Fujieda sisters in Sakura Taisen, Ayame and Kaede (but not at the same time; Kaede is the convenient substitute when Ayame becomes unavailable, from Sakura Taisen II onward). Ratchet Altair plays the role in Sakura Taisen V.
 * Though Ratchet is romanceable, subverting the trope.