Female characters in Age of Conan don't wear bras. This can be seen every time when using the "Hide" ability, as hiding makes your equipment turn transparent.
In Another Eden, Cyrus's pants have triangular spacings exposing his waist by the sides and viewing his 5* artwork based on anatomy, it is likely that Cyrus doesn't wear any underwear beneath his pants.
While the Ship Girls in Azur Lane have a quite a few examples in their default or paid skins, the most notable and infamous example of this is St. Louis in her "Luxurious Wheels" party "dress" outfit. Both the main menu animation as well as official art◊ make it clear she's not wearing anything under that already flimsy piece of clothing.
Bayonetta: Like in the Morrigan example above, the titular heroine Bayonetta's witch outfit is entirely made of hair that leaves her exposed as she performs Wicked Weaves. When she summons a monster, it's exceedingly obvious she does not wear undergarments.
Feral from BloodRayne 2 is covered only by what appears to be a deep indigo vapor on the surface of her skin. Since she and her animated Body Paint tend to move capriciously, Theiss Titillation Theory is heavily applied with Nipple and Dimed up top and Barbie Doll Anatomy below, while leaving her rear more casually exposed at times.
Bravely Default has the Bravo Bikini, which the party tries to get Agnès to wear so she can win in a beauty contest. Since the goal was just to get the attention of the vestal of water, and Agnès finds the bikini embarassing, she ends up not wearing it, but it can be unlocked as an alternate outfit for Edea. The US version Bowdlerized it by censoring the outfit and aging Edea to eighteen rather than fifteen, but it does remain skimpy. To give you an idea, here's a comparison, with the uncensored version to the right◊.
Morrigan deserves a special mention. Since her clothing is made up of servant bats that conform to her body and change appearance, everything she wears is Vapor Wear. Then again, she is a succubus.
Felicia the Catgirl also qualifies. The fur on her body is part of her body itself, and she has the ability to control where it even shows up at will (same with her ears, claws, and feet: she can turn them completely human at will). She is technically naked in every aspect. Even her ass is fully exposed, but sometimes gets censored just enough by various means during her attacks.
Gloria in Devil May Cry 4. Her outfit leaves little room for imagination, the camera angles deliberately make it unclear whether or not she's wearing panties, and she seems almost content to let onlookers gaze at her. When Dante meets her, he has a hearty laugh and comments that the look suits her, while Gloria retorts that she dresses to impress. Then she reveals that she's Trish in disguise.
Another Morrigan, this one from Dragon Age: Origins, fits this quite well. Though it works out pretty strangely with the universal undergarments the game uses for undressed characters, as she ends up basically putting on a bra for sex scenes and covering more of her breasts up than her default outfit does. By her appearance in the third game she's acquired just enough extra material to justify her not being bare-chested every time the wind blows. Given it's the look she had in her concept art, this may just be a result of the graphics update.
In Skyrim, many of the female characters, most notably Aela, sport this trope. Unless of course you remove the armor from their dead bodies then some underclothing magically appears.
Penelo in Final Fantasy XII: Revenant Wings wears harem pants and a tiny crop top that make it highly unlikely that there is any underwear involved.
Played with confusingly for Serah Farron in Final Fantasy XIII-2. Her new outfit◊ makes it clear she isn't wearing a bra under her short dress, and there are large cut-out parts near her hips, implying she isn't wearing anything underneath. But official material and the in-game camera prove that she wears black biker shorts underneath, despite them not visible at the cut-out parts.
In the leaked prototype for the 7th game, the CG pictures don't have the grainy filter applied yet and make it easy to see Lyn's bare right cheek under her dress.
In Awakening, we have Aversa who has a Navel-Deep Neckline that makes it clear she has no bra, but there's also Tiki, whose entire dress is cut in a fashion that implies she might be going commando. Naga herself is not immune to this either, at least in regards to her upper torso, as all Awakening artwork of her shows that area semi-exposed and she clearly isn't wearing a bra.
Gaia Online has the Laceback Skirt, a miniskirt that amounts to two squares of black leather and lacing up the sides (the name references the Laceback Bootsnakes you get the materials from in zOMG!). Admittedly, Gaia Online also has articles of clothing that amount to strategically-placed clouds, "Heart Pasties", and "Porn Stars", so this is nothing new.
NPC Sasha used to wear a short sarong so low on her hips that any underpants she was wearing would have been apparent. After the Art Shift, she's switched to jeans and a t-shirt. Post-Art Shift Ruby, on the other hand, clearly isn't wearing a bra under her new dress (for obvious reasons, since she now has angelic wings). This is a bit more alarming than the other examples since Ruby is A) quite stacked and B) the single mother of a young boy.
A common design element in Genshin Impact, such that Collei becomes notable among the cast for wearing a visible bandeau-style bra. Prime examples of this include:
Eula Lawrence has a see-through opening on the sides of her skintight outfit and matching her Navel-Deep Neckline, showing she doesn't wear a bra and panties.
Shenhe's skin-tight outfit also showcases her curves and has two windows at the sides of her hips, showing that it's impossible for her to be wearing panties.
In Gladiator, in the Japanese release (and the initial USA release), it becomes evident that Irene is not wearing a bra under her armor after her breastplate is broken.
I-no in the Guilty Gear series goes braless, in a top that realistically would show the goods to anyone she was fighting.
Some of the more Stripperiffic battlesuits in Honkai Impact 3rd are cut in ways that make it clear that the Valkyries are not wearing anything under them. Bronya's Yamabuki Armor and its Palette Swap Throatwort are two of the most egregious cases, as their bottoms are so low-rise that they leave the top half of her butt completely exposed.
Mass Effect 2 character Jack wears only some narrow leather straps (and a lot of tattoos) above her waist; a later alternate outfit and her clothes in Mass Effect 3 at least cover her breasts, but are still tight-fitting enough to show major nipplage.
In Mortal Kombat vs. DC Universe, most of the women are decently clothed, though significantly bouncier than one would expect in armor. Catwoman, on the other hand, clearly isn't wearing a bra (and her catsuit is unzipped practically to her navel). Neither is Wonder Woman. As this is the skimpiest of Diana's outfits (completely backless leotard with a very high-V bottom), we can also say that she is probably not wearing anything under it, especially since thongs weren't invented in Ancient Greece. Sonya clearly isn't wearing a bra under her crop-top, as the outlines of her nipples are incredibly visible.
In Mortal Kombat 9, most of the women aren't wearing underwear. Jade, Kitana, Mileena, and Skarlet all wear too little to actually fit any bras or panties under their skimpy outfit, and it shows. Sonya's first costume doesn't have a bra by default, and the damage to her pants shows that she isn't wearing any panties either. Same goes for her second costume, where you can actually see the outline of her nipples against her tank top, and while she doesn't wear any panties, she was given some Tan Lines on her butt.
The models for female characters in the original Neverwinter Nights are set up so that they are always wearing underwear unless you have an item equipped in their armor slot, in which case the underwear disappears. Curious, given the presence of backless/excessive cleavage torso options for most armors.
Hibana of Nightshade (2003) covers most of her body in a similar ninja suit as Taki, with some strategically placed "breathing gaps" seemingly just to confirm that there's nothing underneath.
There was a brief period in time for Nintendo's male RPG heroes where they would wear not much more than a short, flimsy tunic. In the case for the original design◊ of Fire Emblem's Marth or Link's various Young◊ and teenage◊ designs, they were often so short that you were left wondering if they were wearing anything at all. Some of Young Link's 3D models would even have what's under his tunic censored out, strengthening this trope even further.
Persona 5 has Shadow Sae. Long black dress with a slit up the side, and a plunging neckline with sheer fabric covering skin that would otherwise be completely exposed. This makes it plainly obvious she's not wearing a bra.
The heroine of Psychotoxic averts this in the actual game, but plays it straight in the box art. Her low-rider jeans clearly show she wears a thong in-game, but the identical outfit on the box shows no thong.
Excella Gionne from Resident Evil 5 clearly has nothing underneath her backless dress.
In Resident Evil 6, there's a section of the game where Sherry is in a skimpy hospital gown with a Navel-Deep Neckline and Sideboobs, with no bra in sight. She does get some white panties, so she isn't going completely without underwear.
In the Saints Row series, clothing customization includes underwear, and in Saints Row 2 and later, you may go without. Depending on the rest of your outfit, Pixellation may be applied as necessary.note Although may be bypassed with just a set of pasties and a microscopic G-string Combined with Stripperiffic clothing choices, user-modifiable boob size and Jiggle Physics for maximum Fanservice.
Scarlet Blade has the Arkana who are all female(save the male Cyberblade class). They wear high tech armor that barely covers their bodies, and they also have lingerie that are more revealing than g-strings. The rest of the worlds npc's wear even more revealing clothes especially in the Delilah Nightclub.
In The Secret World, female characters are by default not wearing bras. Many outfits include bras, or you can choose to wear a bra instead of a shirt. In early versions of the game, many player characters, male and female, wore only an open jacket or coat without anything underneath. This led to complaints and was later fixed so that women always have to wear something in the "shirt" slot (even though the "shirt" can be just a bra or a bikini top).
It may be justified, due to her wings, but it's pretty clear that Rouge the Bat from Sonic the Hedgehog doesn't wear a bra.
Numerous outfits for the female custom characters in Soulcalibur IV appear to be worn without underwear, complete with a Navel-Deep Neckline. Of course, when Clothing Damage kicks in, a bra will spontaneously appear where there clearly wasn't one before.
SOUND VOLTEX has numerous jackets with female characters wearing close to nothing bar something like a scant swimsuit, but some characters are egregiously notable for doing this.
Grace, the Big Bad from Gravity Wars noticeably wears nothing bar some clothing that only covers a small part of her chest, waist and hips by default. While starting from Heavenly Heaven when she becomes integrated with the main cast, her default outfit(s) are not this level of scant, she's still sometimes drawn in jackets with suggestive outfits.
Yamashina Kanade's default outfit is nothing more than a naked apron and a pair of panties under it (the latter not even being visible in some angles). It's also clear that she never wears anything to cover her chest bar an apron.
Chun Li and Cammy in Street Fighter IV have visible nipples during battles. They even bounce. Oddly, Chun Li is depicted with underwear nearly all the time, except during battle. Hmm.
Ezana from Triangle Strategy is wearing pelts stitched into a dress; the gaps in the sides pretty clearly show that she's not wearing underwear. It's also cut in a way to reveal a lot of her bare back and a bit of Sideboob.
Many outfits produce Navel-Deep Neckline when worn by female characters - robes, mostly, but also some plate armor. In most cases you can wear a shirt underneath, but the bras worn by all "nude" female character models magically disappear as soon as you put on clothes. Some leg armor is crotchless on characters of either gender, so it is also possible to create an outfit where only the belt covers the crotch.
Sally Whitemane's shoulders and her crotch are only barely covered, so there's just no way she's wearing undies.
Siouxie the Banshee in Acherus is also definitely not wearing underwear, but then again she's dead.
Most female Night Elf NPCs who are not wearing armour wear backless or very low-cut tops (often with a Navel-Deep Neckline) and clearly no bras.
Many orcs and trolls don't seem to bother much with clothes: they tend to wear what amounts to a survival harness plus any armor they think they might need. The female version of the harness is slightly more covering but leaves no room for any undergarment.
◊, who's very, very clearly not wearing anything under her outfit. Though considering there's not much to the outfit to begin with...
