Masculine Lines, Feminine Curves

Masculine Lines, Feminine Curves is about more angular, more square and more muscular men, male animals, aliens, monsters, fantastical and mythical creatures, and robots and more curvaceous and rounder women, female animals, aliens, monsters, fantastical and mythical creatures, and robots. Female characters can be angular, but they are usually curvier and less square than male characters.

Bird and mammal characters in the lower end of the Sliding Scale of Anthropomorphism (from Nearly-Normal Animal to Funny Animal) tend to be given chest ruff for these purposes on females to give a distinct Non-Mammal Mammaries look.

Female characters might also be given Hartman Hips.

This is a foundational trope for character design in comics. Part of the problem with human examples is that they are so pervasive! It's very common for (human) male and female characters to be clearly differentiated with exaggerated straight-line, curved line designs to the point where we don't even notice any more.

For animal examples, please only list examples that are both on the same (or at very similar) level(s) on the Sliding Scale of Anthropomorphism; examples where female animals are actually more anthropomorphic than male animals and not merely more curvaceous go under Humanoid Female Animal.

Film

 * The short, nearly cube-shaped Carl Frederickson of Up contrasted with his wife Ellie. Even their chairs reflect how they look physically.
 * Though that may be a reflection of their temperaments. Russell is also very round and egg-shaped and he's a boy.
 * Who Framed Roger Rabbit: Ultra-feminine Jessica Rabbit's design is a collection of curves. As well as her more obviously globular features, her hair falls in curves across her face.
 * Several Disney animated films such as Sleeping Beauty, Pocahontas, Hercules, Mulan, The Emperors New Groove, Atlantis the Lost Empire, and Home On the Range.
 * This is played with subtly in Mulan. Whenever Mulan is in her male soldier disguise her jawline is angled slightly.

Newspaper Comics

 * Dick Tracy's visual signature is his ultra-manly rectilinear chin and nose.

Web Comics

 * Dresden Codak: Ron Awning's character design is based on triangles. Kim Ross is based on circles and soft curves.
 * Aaron Diaz, creator of Dresden Codak, writes a blog called Indistinguishable From Magic where he discusses comics. This artwork from the blog - specifically, from the figure design essay - seems like a good illustration of the trope. (Though the discussion was about the need for instant recognition in design rather than male-female design; Ron's sister Vonnie, not shown on this trope page, is made up of arches and triangles.)
 * Order of the Stick has rectangular, straight-line models for male characters' torsos and curvy rounded models for female characters' torsos.

Web Original

 * Even though they're not like this in real life (as they're, well, human), the title cards for The Nostalgia Critic and The Nostalgia Chick reflect this style. The Critic is drawn thin, angular and with very hard lines although the man himself has quite a soft face, while the Chick is placed in just as silly situations but is drawn with Curves in All The Right Places.

Western Animation

 * On Clone High, male characters are drawn with boxy frames and straight lines, and rectangular fingers that end with an edge. Female characters are drawn with curvy frames, including Hartman Hips and curved fingers that end in points.
 * Batman the Animated Series and anything else with designs by Bruce Timm. His male characters are always extremely blocky compared to the curvy women. Men often have square jaws, square hairlines, even square ears! Meanwhile, women look like they've been poured into their outfits.
 * Phineas and Ferb is a particularly clear example. Phineas is blocky with a triangular head; Doofenshmirtz is the the same but his edges are rounded off. Ferb, Lawrence and Major Monogram are made of a series of boxes. Candace is quite angular but has a round face; Isabella and the Fireside Girls are similar. Linda and Vanessa are all curves.
 * Total Drama Island/Action/World Tour
 * Dexters Laboratory: Dexter is a very boxy kid, and Dad has a rectangular face. Deedee and Mom have more rounded face and body lines (especially Mom's Hartman Hips).

Film

 * Female emperor penguins in Happy Feet look a little more curvaceous than the males. They also have feminine shading on their chests, which the male penguins don't have.
 * Pongo from One Hundred and One Dalmatians has more pronounced shoulders, a squarer snout, and straighter lines than his mate, Perdita. In contrast, Perdita has a more delicate chin, rounder shoulders, and a more curved, slender body.
 * Scratette from Ice Age: Dawn of the Dinosaurs has Hartman Hips and looks more curvaceous than Scrat.
 * Shows up with the animals in Home On the Range.

Western Animation

 * This shows up in the facial structures of the ponies in My Little Pony Friendship Is Magic.

Video Games

 * Pokémon plays this straight with Gallade, whom due to it being a male-only species, has and completely angular body, but subverted with the more feminine-looking Gardevoir (and to a much lesser extent, Kirlia), where despite having a curved body, can actually be both genders. Ralts, on the other hand averts this as it appears to have a gender-neutral appearance.
 * While both are genderless, Reshiram and Zekrom were designed as polar opposites, with one of them being that they are designed to have feminine and masculine features respectively.

Film

 * The Greek gods and goddesses from Hercules.

Film

 * WALL-E and EVE fall into this pattern. He's boxy, she looks like she was made by Apple.
 * The masculine and feminine shapes of Wall-E and Eve was even highlighted in the credits. The eight-bit versions of them start out as a brown square and white ellipse.
 * The other Axiom robots who are (presumably) male are more angled and squareish too.
 * Cars (also by Pixar) actually did this with the characters' windshields. Male cars have angular eyelids, while female have curved eyelids.
 * A more straight example would be Shu Todoroki the Japanese racecar and Carla Veloso the Brazilian racecar from the sequel. While the two cars both appear to be of the exact same make and model, Shu, being male has a more angular appearance, while Carla, being female has a more curved appearance.

Video Games

 * In the Mass Effect franchise, the asari are a One-Gender Race of all women. Their technology and architecture are always depicted as sleek and curvaceous, compared to the other races of the galaxy.

Western Animation

 * Most of the Transformers from Transformers Generation 1 are male and drawn in straight lines. The few (toyless) females are generally curvier, but so are nearly all the males not drawn after a toy.
 * Though it is subverted at times, this is the general pattern for the manbots and fembots of Futurama.