Despite their complete lack of skin and muscle, characters with their bare skulls for a face can express their mood with their eye sockets and jaws just as well as any other flesh and blood character.
Even though the skull is a mostly static set of bones, many creators, particularly in animation, opt to have their skeletal characters have the ability to bend and stretch their eye sockets and jaws to in order to make them seem more lively. They can furrow their eye sockets into an angry expression or widen them in surprise as if they still had eyebrows, their jaws can bend into a scowl or a big smile that ends at the cheekbones and so on, as if it's the bone that creates the facial expression and not the muscle.
Compare to Expressive Mask. Mouthy Bird is technically a subtrope. See also Skull for a Head, where this trope is usually used, and Dem Bones if the rest of the body also happens to be nothing but a skeleton.
- In The Book of Life, the residents of The Land of the Dead are depicted as skeletons whose faces are almost no different than the faces of living people, aside from being made of bone, having empty sockets with glowing pupils, and having no nose. As such, the undead have exactly the same range of emotion as the living. Possibly justified, seeing how the story is being told using wooden puppets.
- In Coco, the spirits of the dead appear as skeletons, but they can contort their mouths and eye sockets to make expressions. It helps that they have eyeballs. Justified by the fact that they're spirits, who obviously do not conform to logic of the human world.
- Jack Skellington from The Nightmare Before Christmas uses this, although it's questionable whether Jack is actually a skeleton or is a living creature that happens to resemble a skeleton.
- Mr. Skully Pettibone from Scary God Mother frequently raises his 'eyebrows' and blinks.
- Zigzagged in Overlord. In-universe Ainz is grateful for his Lich body's unmoving skull, since it gives him the ultimate poker face in situations where he has to bluff being more ambitious, intelligent or in-control than he actually is (which is always). From the audience's perspective, he still manages to show quite a bit of his true emotions through careful use of camera angles and varying the glow of his eyes, and occasionally through blushes and nervous sweating, or the entire panel going for the Super-Deformed look.
- The Character Portrait for Breath of Death VII's skeletal protagonist Dem shows him with both eyebrows... er, eye sockets furrowed.
- T-Bone, the giant skeletal train conductor from Cuphead, rises with a furious attitude, constantly shifts his eyes sockets as he searches for the player, and sports a big smug grin in his defeat card if he successfully kills the player.
- The skeletons from Darkest Dungeon shift from malicious looks on their skulls as they ruin your party to pained and worried expressions when they're taking hits.
- In Discworld II, Death and other animated skeletons do occasionally exhibit the ability to contort their eyebrow area and eye sockets to show some degree of emotion, as well as being able to blink with eyelids that are apparently part of the skull. It is kept toned down though, as they generally keep a neutral expression.
- In DragonFable, many skeletons have expressive skulls. The most prominent one is Captain Davey, an undead pirate who's eye sockets can narrow and widen.
- Heroes of the Storm featured a downplayed example of this trope during the reveal trailer for Kel'thuzad. Blizzard Entertainment went with an Animesque style of animation rather than a more traditional one. This included Kel'Thuzad making his Glowing Eyelights of Undeath squint and his face contort in an evil grin.
- Papyrus from Undertale has eye sockets that bend around on his face as he lacks the glowing eyes that his brother Sans has, which can even grow eyeballs in their place if he gets particularly frustrated/goofy. The brothers also have mouths that are permanently stuck in joyous, cheek-to-cheek grins befitting their personalities.
- Morte in Planescape: Torment is pretty good at conveying facial expressions despite being a talking, floating skull that can only move his jaw and eyeballs.
- Lewis from Mystery Skulls Animated typically looks angry (and he usually is) with his eye sockets, though on occasion they relax into more somber moods.
- Xykon of The Order of the Stick is a lich and his skull is surprisingly expressive, even if it can't do an Evil Laugh. Of course, the rest of his body is also moving more than a normal skeleton. This page has his eyes change from their default "snarky" shape to wide with shock.
- The beleaguered reaper Mye argues with after Zeno kills her in Charby the Vampirate is quite expressive when coming across the spirits that make his job so thankless.
- Full Frontal Nerdity: During a story arc involving a lich, just about everyone at the table points out this trope.
- DC Animated Universe: Atomic Skull in Justice League Unlimited and Blight in Batman Beyond both have skulls for heads, which tend to be just about as expressive as every other villain.
- Grim from The Grim Adventures of Billy & Mandy uses this to downright silly degrees, even forming lips with the rims of his teeth/jaws at some points, as seen in the page image.
- Skeletor of He-Man and the Masters of the Universe is usually stuck with a permanent angry expression over his eye sockets, but occasionally he can show other expressions beyond anger, and in one rare case, even form a warm smile.◊
- A Real Magic Skeleton from OK K.O.! Let's Be Heroes has the "eyesockets as eyebrows" variant, though sometimes he'll just be given actual eyebrows. His mouth also makes a half zero, which stretches and compresses depending on his mood.
- Lord Hater from Wander over Yonder is a large green eyed skeleton in robes, and yet he's just as fluently animated as the rest of the cast.