Leif Loud is the male version of Lana Loud.

1. Appearance: Leif wears a red baseball cap facing backwards, white sneakers, and blue overalls. Unlike his female counterpart, Leif's blond hair isn't styled into pigtails. Leif, unlike his female counterpart, is missing his canines instead of his incisors. He also isn't wearing a shirt underneath his overalls. Also, his overalls are shorter than Lana's overalls. His hat also appears to have a more rectangular hole, compared to the more round hole on his female counterpart's hat.
2. Personality: Like Lana, he is rough and messy. Like the Loud brothers, he is rude, aggressive, mean, harsh, and always likes to dogpile on anyone no matter who it is. However, in the world where the brothers have a sister named Linka, Leif and the rest of the brothers are shown to be just as caring and protective of her as the Loud sisters are of Lincoln.

Trivia:

1. Much like their female selves, he, Lexx, and Leon are all voiced by Grey Griffin.
2. Leif, along with Lexx, are the only younger brothers to be voiced by male dubbers in the Latin American dub, in that case, by the same one (like their female counterparts).