Leni L. Loud is a main character in The Loud House.
At 17-years-old (16-years-old before Season 5), Leni is the second oldest child of the Loud family. She is very naive and quite ditzy, but she makes up for it with her beauty and kindness. Leni is a senior (a junior in Seasons 1–4) at Royal Woods High School and attends school with her siblings Luna and Luan.
Despite being the second-oldest of the Loud children, Leni is quite ditzy and is very forgetful, absent-minded, and perky. Various examples of her simple-mindedness are expressed throughout the series. In "Linc or Swim," she does not know the rules of the game, "Marco Polo," much to Luan's annoyance. In "Project Loud House," she is shown to be unable to walk and chew bubble gum at the same time. When she's being interrogated by Lincoln and Lucy in "Sleuth or Consequences," she thinks they are interviewing her, and states that her favorite color is "zebra."
Her ditzy nature has also caused her to behave like a child, such as in "Changing the Baby," where she gets stuck in Lily's crib, calls it a "baby prison," bawls like a baby, and then gratefully says "agoo" once Lincoln and Lori get her out; and in "Sitting Bull," where she gets an "ouchie" (a term for when babies and young kids get hurt) and is then cheered up when Luan hits herself with a hammer prop, which she does to cheer up the children she looks after when babysitting. In "Schooled!", when she accidentally attends preschool, she starts behaving like the other preschoolers to the point where she's even sucking her thumb while taking a nap.
Despite being ditzy and absent-minded, Leni's shown to be skilled at fashion designing, wood carving, singing, lock-picking, and making smoothies, which demonstrates that while she may not be very bright, she is creative and artistically inclined. She is also very friendly and gets along well with her siblings.
Leni is arachnophobic. This phobia is most prominent in "Along Came a Sister," where Lincoln brings his class's pet spider, Frances, home. When Leni first sees Frances, she panics and attempts to kill her with bug spray. Later on, it is revealed that Frances is still alive, and Lynn Sr. – who is also arachnophobic – hires an exterminator to dispose of her. Leni faces her fear and cuts off the exterminator, in order to save Lincoln's reputation – once again – showing that she does have a big heart.
Leni has also proved that she can be irresponsible, as shown in the episode "Cover Girls." She agreed to cover for Luna, Luan, Lynn, Lucy, Lola, and Lana, and later passed the task onto Lincoln. However, Leni is shown to be very compassionate, as she was the only one of her siblings to prioritize helping her family get better, as opposed to getting away when the Loud family caught the flu in "One Flu Over the Loud House." In addition, in "No Spoilers," it is shown she is the only person in the family considerate enough in the family to be able to make the perfect surprise party because she pays attention to what people like (excluding the surprise part since she always spoils the surprise because she cannot keep it a secret due to her ditzy and naive personality).
Sometimes, she is too nice for her own good. In "Shop Girl," she let a bunch of shoppers take her stuff and was not even upset about it, saying that she would just make some new clothes out of her old ones. Though her siblings taught her to be tougher, she decided that she likes being nice more, as she gave some of the clothes she bought away to people who needed them more. In "Everybody Loves Leni," she worked very hard to bring her work friends and school friends together. She felt guilty for all the arguing between them and punished herself by missing out on her favorite sale, but her friends decided to get along for her sake.
Leni has long, pale-blonde hair, with side-swept bangs, and three pairs of eyelashes. She is almost as tall as Lori, but taller than all her younger siblings.
Her main outfit is a seafoam green dress, with white frills, and triangular sleeves. With this, she wears red hoop earrings, white slide slip-on sandals, topped with light green bows, and a pair of rounded white sunglasses with black lenses on top of her head.
One interesting note about what Leni wears is that the color of the bows on her sandals change to correspond with what she's wearing. In "Ties That Bind" and "Brawl in the Family," the bows were blue to correspond with the tank top and dress she was wearing. In "Tricked!," the bows were white to match the circa 18th-century dress she was wearing while as Marie Antoinette.
Leni's swimwear is also seafoam green with white frills, only it is a two-piece garment. The top half has two simple straps, while the bottom half is longer than the top, and has four white buttons. Instead of sunglasses, she wears a seafoam green swimming cap, with a white bow tie. She retains her earrings and sandals, even while in water.
Her night attire consists of a seafoam green nightgown, that looks very similar to her regular outfit but sleeveless. She also sleeps with a magenta sleeping mask, but later on, it changes to a blue mask, with an image of closed eyes over it. She retains her magenta mask, and like the blue one, it has the closed eyes image.
Leni's original design depicted her with a light blue dress, snow boots, as opposed to sandals, and a hairstyle that resembled Lori's, but was slightly longer.
In "Hand-Me-Downer," she was seen as a younger girl, but her wardrobe wasn't entirely different. She still wore a seafoam green dress and sandals with green bows on them. The only differences are that her dress didn't have frilled sleeves, and she didn't have her sunglasses.
In "Selfie Improvement," she was seen as a younger girl again. She wore a seafoam green shirt, brown cargo shorts, white socks, and seafoam green shoes.
As of Season 4, her nose has a rounder shape.
Leni wears her sunglasses atop her head in every episode she appears in. She only removes them when she goes to bed, showers, goes swimming or goes outside in the snow.
Her sunglasses are white, with two black circular lenses, and a shine going across both of them.
When she was portraying a cat in the family play in "Suite and Sour," her sunglasses were triangular in shape, rather than circular, which looked like cat ears. This means that she owns more than one pair of sunglasses.
There is an animation goof that has occurred a few times, where her sunglasses are missing in one shot, and then reappear in the next shot.
Alternate Versions and Alter-egos
In the second alternate universe, where it's one girl and ten boys, Loni's shown to be very caring towards Linka, Lincoln's female counterpart—in fact, Loni's the one who makes the offer of him and the rest of the brothers staying with Linka until she falls asleep after they heard her screaming in the middle of the night.
Loni eventually turns out to be a product of Lincoln's imagination as it is revealed Lincoln's whole adventure was just a dream.
After finding a hotel worker's name tag in "Suite and Sour," Leni immediately likes the look of the tag and decides to put it on, fooling every hotel customer that walked by her, as the name tag says "Fritz." When the customers start to treat Leni like an actual worker, Leni decides to work as one too, giving her customers the keys to their rooms, and addressing the customers' complaints. She even tried to kick the Loud family out of their room because of reports from angry customers.
The 11 of Hearts
In the minicomic Deuces Wild! and its animated adaptation, Leni takes on the identity of the superheroine "The 11 of Hearts." She plays the role of one of Ace Savvy's sidekicks. Her signature weapons are heart ties with which she uses to tie up her foes. In the comic, she is summoned by Savvy alongside the rest of his deck to help him and One-Eyed Jack to defeat the gas monster. After they defeat it, they prepare to fight against a garbage monster. This turned out to be Lincoln's fantasy, based on him and his sisters changing Lily's diaper and taking out the trash.
The 11 of Hearts appears once again in "Pulp Friction," along with the rest of the Full House Gang. During her appearance in the episode, she saved Ace Savvy and One Eyed Jack from falling into a shark pit by using her pink bow as a rope.
In "Kings of the Con", Leni attends a convention dressed as the Eleven of Hearts.
The Eleven of Hearts wears heart-shaped sunglasses, a dress like Leni's usual one but with poofy red sleeves and a white skirt, high black boots with teal rims, and a large pink ribbon with hearts on it tied around her waist. Her name comes from the heart suit in a deck of cards, and that she is the "heart" (i.e. the moral centre) of the Loud family.