Hisoka in Yami No Matsuei is pretty darn competent but has a softer reputation because he's The Heart in The Team. His empathy is most useful in the episode where he uses it to fake clairvoyance.
Naoya in Night Head Genesis, his case is probably one of the most extreme ever seen in any medium.
Rare for a non-fantastic setting, but Yakumo Tsukamoto (Tenma's younger sister) from School Rumble is able to detect how boys are secretly feeling about her. Teen Genius Haruki Hanai, the one guy vocally interested in her, often escapes her notice.
In One Piece a Kenbushoku Haki user (called also Mantra) can work this way. Both Aisa and Otohime are able to sense negative emotions of people around them. Some users, like Otohime, act upon these sensations and try to help. This power can also turn out to be pretty nasty one, if a user isn’t able to control it. Coby learnt it the hard way.
Mito Uzumaki from Naruto was able to sense the negative emotions of people around her thanks to the Nine-Tailed Fox inside her. Naruto develops the same power later in the series.
In Variable Geo, Yuka is able to get glimpses into the mind of her opponents when she gets hit by their Ki Attacks. She gets disturbed when this doesn't work on an opponent.
In Bleach, Ichigo can sense the feelings of his opponents when their blades clash. This is why he feels no real satisfaction after defeating Aizen. He feels nothing but pity for his defeated foe after sensing his soul crushing loneliness.
Raven in the original New Teen Titans comic book started out with this power, in addition to healing, teleportation, and some spellcasting. She was useless in combat and was always the first to be knocked out. It wasn't until the success of the cartoon that she was given flight and telekinesis.
Empath (Manuel de la Rocha) from New Mutants is a genderflip. He could control emotions in addition to passively sense them.
Meggan, of the Marvel team Excalibur, was The Empath and since her (mostly) Voluntary Shapeshifting powers were tied to her emotions, she often changed to reflect people's expectations of her. Eventually, other people's expectations no longer affected her.
Cordelia Frost (sister of X-Men's Emma Frost) possesses the power of empathy. Described as the "Professor X of empaths" Cordelia can not only sense the emotions of others but implant emotional states into them, shoot mind bullets and even use her powers for makeshift mind control by implanting an entirely new personality into someone. Somehow....
CrossGen's The First had Pyrem, a diplomat whose powers were described (but not often shown) as empathic. Crux had empathy as the fifth Atlantean discipline named empathy, but it manifested as Voluntary Shapeshifting.
The Authority's shaman "the Doctor", had this power, as well as incredible amounts of magic, as a result of an acquired connection to all life. Particularly interesting for the origins of the various Doctors shown in the comic- an utopian anarchist, a dotcom billionaire drug addict, and an islamic suicide bomber. It's explained that the powers go to the one person in the world who wants them the least. The suicide bomber was about to set himself off when he acquired his powers: Bang! instant Heel-Face Turn. Not only of himself, but he immediately used his powers to create peace in the Middle East
There was also a renegade former Doctor who was defeated by being given all the powers of the Doctor. From unstoppable rampage and serious inroad into the world's supplies of Dom Perignon to gibbering horror at the suffering he had caused in one fell swoop.
In the same universe, Charis, sometimes called Nemesis, is this. For a female with empathic powers, she is quite the opposite of useless. Her empathy allows her to briefly delve into the thoughts of a target, and allows her to anticipate and react against her universe's version of Superman. Yes, she was able to dodge and cut Mr. Majestic.
This is sort of Man-Thing's deal. He's a superstrong being made of plant matter, and if his body's destroyed, he can reconstitute himself in his home swamp. But he also senses emotions; in general, he doesn't like negative ones. Specifically, fear causes him to immolate tings; hence the tagline "Whatever knows fear burns at the Man-Thing's touch". Though despite the fact that he's a mindless swamp creature with an appearance that borders between terrifying and Ugly Cute, typically only bad guys get incinerated, bystanders don't.
Madman has been able to do this, which helped him determine of an alien was aggressive or not.
In the W.I.T.C.H. comics, Will had this power with animals; that is they react to her mood and at least one parrot who could speak in English/Italian (the latter being the original language) could literally read her mind. This power is missing in the show though.
The Black Lanterns in Blackest Night have the ability to see the emotions of living beings. As part of their MO involves ripping out the hearts of living beings to fuel their powers, they use this ability to manipulate the victim into strongly feeling one emotion, then ripping out their heart in that state so it will provide a charge.
In addition to their more obvious powers, the Emotion Entities introduced in the Green Lantern series have empathic powers. Parallax can sense and manipulate fear, the Butcher feeds on and instigates rage, Proselyte induces compassion into others, etc. They can do all of this because they are those emotions.
In Firing Range, the tank being tested can sense hate and fear, and extends that sensing into reading minds in order to avoid attacks and how to kill the enemy.
In the Final Fantasy VII fanfic Thorns there is an OC that is later revealed to be an Empath. Originally, it isn't very obviously and weak. Then he gets shot up with Mako. He generally uses it as Combat Clairvoyance, but in certain cases it's a weakness. He ends up using another person as an "anchor" to help him survive the power boost he got during the storyline.
The best part? "I sense I'm going down!" (after her plane has just been shot down)
Films — Live-Action
Most (if not all) Jedi are empaths, but to what extent depends on how Force-sensitive one is, as well as their personality. This one has the downside of causing a psychic backlash if the user is overwhelmed by it.
May also be exploited by enemies. The most poignant example would be in Revenge of the Sith where the Jedi didn't see the Clone Army's betrayal coming because the clones had no emotional motive like exhilaration, hatred, or fear when eliminating the Jedi—it was all coldly business to them.
Atton Rand is pretty blunt about how he is able to use walls of basic emotions — anger, lust, etc. to shield himself from most Jedi mind tricks, as well as how effective it was in his previous life as a Sith hunter/torturer.
Indeed HK-47 in Knights of the Old Republic II notes people capable of projecting strong emotions are best able to hide their intent and surprise attack jedi. Revan appreciates the irony that those who experienced emotion were best able to take on the jedi who suppressed it.
The Expanded Universe has the Zeltrons, a race full of empaths. They're a slight subversion as it doesn't cripple their ability to fight, and it doesn't really cause them pain. Their society places a high value on joy and pleasure (especially sexual pleasure), and is widely considered a "party planet." Most invaders to Zeltros quickly found themselves partying with the natives instead of conquering the place.
Dan Smithson, the character played by Forrest Whittaker in the sci-fi film Species, is an empath, although he's played up as more of a Captain Obvious. His power also has a tendency to only work as the plot demands it, such as when he's able to sense someone outside a door and the emotions of the alien hottie while watching a recording of her, but they mysteriously vanish on numerous occasions, such as when a wino manages to catch him by surprise by hiding behind a dumpster.
In Isaac Asimov's Foundation series, the Mule became a Big Bad because he's able to Brainwash his enemies into completely loyal servants. Unlike most mind-controlling telepaths, he's unable to read minds for specific information, but he can overwrite the emotions most Brainwashed servants would use to break free at a crucial moment.
The showcase character for Empathy is Talia, protagonist of the Arrows trilogy. At first, she doesn't know how to control her power and has a hard time finding anyone who can properly train her in it, leading to a lot of heartbreak as she nearly kills herself and others. Even after she manages to train herself properly with the aid of a Gift instructor, she struggles with the morality of it, such as whether it's acceptable to read the emotional state of a Councillor and use that against him — or worse, influence him directly. The most aggressive use she makes of her power is to literally Mind Rape a man who had raped his daughters into experiencing it from their perspective in an endless loop until he repents. She otherwise functions as the Queen's Own Herald, a confidant and key advisor to the Monarch, and is considered The Heart of the Heralds in general.
Most Healers have Empathy as a component of their Gift; in fact, a key sign that someone is developing the Healing gift is if they start to manifest empathy. This can drive them mad if not detected and trained early enough, as they become unable to separate their emotions from those of other people. In The Black Gryphon, both Amberdrake and Winterhart are victims of this in their respective backstories; each requires intensive therapy to resume a normal life.
Vanyel Ashkevron in The Last Herald-Mage is a latent Empath, along with his other talents. When his mental and magical channels are blasted open due to a magical accident, his suicidal agony is so great that he has to be sedated lest he incapacitate half the Herald's Collegium.
Hadanelith in The White Gryphon is a rare example of an evil Mindhealer; he uses his powers to manipulate people into "willingly" enslaving themselves to him as well as to determine the most effective ways to torture them.
Bards employ a form of projective Empathy that manifests itself through their music, allowing them to make their audience feel the emotion of their songs. The Bardic College requires extensive coursework on the ethics of using the gift.
The treecats in Honor Harrington have an empathic link with their adopted humans, but can also sense basic emotions of other people around him. Combine that ability with their agility, claws and fiercely protective nature of their adopted human, and you get a cute, fuzzy Killer Rabbit that tears out the throats of well armed, disguised assassins.
In James White's Sector General series, Doctor Prilicla is a member of an empathic insectoid race; he finds it distressing to be in the presence of strong emotion, and acts as a peacemaker in self-defense. He's a case of Heart Is an Awesome Power; uses his empathy to pinpoint the locations of patients who need rescuing, and can use his power to help keep them alive by bolstering their spirits. While it wouldn't be useful for a superhero, it made Prilicla one of the most valuable members of Sector General. He is only able to use his empathy in that way because he has the personal courage to willingly expose himself to others' pain and desperation, not to mention physical danger.
Valashu Elahad of the Ea Cycle possesses the power of empathy which can be not so useful when he's feeling the pain of someone he kills in battle. Potentially his gift could be a powerful weapon to break the wills of other people, but that would going to The Dark Side and being Not So Different to the Big Bad.
Harry Potter gets the creepy version of sharing Voldemort's emotions when they are particularly strong.
The "sensitives" in Ian Irvine's The Three Worlds Cycle. As one character puts it: "Whatever you feel, I feel more."
Greg Mandel from Peter F. Hamilton's Mindstar series is a private detective with empathic powers. He is also an ex-military hardcase and can do some other things with his mind, but he finds his empathic ability very useful when interrogating suspects. He uses word association interrogation and sees when their feeling of guilt spikes.
Interesting version in Robert Silverberg's The Man in the Maze. The titular man gains, as a result of a contact with alien race, an inverted version of empathy — he doesn't receive emotions, he constantly projects his own. All of them, down to and including subconscious ones. As it turns out, these deep human emotions are mostly quite unpleasant... As a result, nobody can stay close to him for any length of time (the strength of the psychic barrage is decreasing with distance), and he has to hide in the nigh-inaccessible maze.
In Jane Yolen's Pit Dragon Chronicles, sheltering in a mother dragon's womb can give one superhuman abilities, including becoming an empath. There is a whole mountain tribe that has killed thousands of female dragons after they lay their eggs, just for the children to have the abilities. If they combine their minds, they can send out a force field strong enough to knock out a grown man.
Sean Stewart has an interesting take on empaths in Passion Play. In the world of the book, there are tens of thousands of empaths all over the world, called shapers. Both the protagonist and the villain are shapers, and the protagonist uses this ability in her job as a bounty hunter, so she can understand the people she is tracking and anticipate what they might do next. Shapers not only feel the emotions of others as if they were their own, they can also perceive people's personalities as a sort of mental image, which varies depending on the individual shaper's perceptions. For example, a shaper who encounters a young and naive person may get a mental image of a young spring leaf, whereas meeting a cold, brilliant perfectionist may evoke the image of a gleaming diamond in that shaper's mind, and meeting an extremely religious person may evoke the image of a candle lighting up the surrounding darkness. Shapers can also experience a form of mental burnout or numbness from being overloaded by emotions, and some of the more psychopathic shapers may try to cause pain in others or commit violence just so that they can feel something again after they experience burnout for too long.
Imriel de la Courcel of the Kushiel's Legacy series. His particular version allowed him to detect "fault lines" in a personality, which he could then exploit to manipulate them. A particularly interesting and well-written example, because it was a potentially tremendously powerful ability which he could have used to take over the kingdom, but never did- principally because he was (thanks to being raised by his benevolent foster-parents) such a nice guy. In fact, he almost never used it at all. His biological mother, on the other hand, was a thoroughly evil murderess who used the same ability to repeatedly try to take over the kingdom.
A male example, in Hidden Talents and its sequel, the protagonist's power is the ability to sense emotions of others. he doesn't realize this power until the very end, and doesn't start using it until the sequel, True Talents, came out.
The Icemen use a variant form of watercrafting that has allowed them to develop their empathic abilities to the point of being effectively telepathy. Unfortunately, this also lead to their conflict with the Alerans- their sensing human fear and hostility towards themselves, and sending it back magnified, wound up creating centuries of continuous, tactically pointless warfare.
Jasper Hale. Vampire from Twilight. Can infuse emotions of other sentient beings and can also feel them. One of the reasons he became a Vegetarian Vampire was because he could feel the pain of his many, many victims.
Played with in Octavia Butler's Parable of the Sower and its sequel. People afflicted with hyperempathy syndrome only hallucinate that they are able to feel the pain of others. The effect is real to them, but they feel only what they imagine others are feeling, so it's more of a psychological condition.
Planet of the Damned's main character had empathy that he used in fights to read the subtle change in his opposition's emotions, effectively predicting their attacks before they happened.
In the Firebird Trilogy, the Ehretans (the ancestors of the Sentinels and the Shuhr) created telepathy specifically to gain this power (and the ability to communicate from mind to mind); the Telekinesis and other abilities were just fringe benefits. The idea was that if everyone understood how everyone else was feeling and what they were thinking, there would be perfect understanding and no more war. It... didn't work out that way.note The ensuing civil war between the Altereds and the non-Altereds very nearly killed everyone on the planet, and left Ehret uninhabitable. And the upper classes of the Shuhr, one of the surviving branches of the Altered, are not a pleasant group of people.
Time Scout's Ianira and Margo have an instant connection thanks to their shared abilities and background, hence Ianira, prophetess and priestess of Artemis immediately wants to train Margo.
Later in the same book, Wagers of Sin, Ianira instantly a man's tears upon waking aren't due to his injuries and weeks of privation, but due to the sorrows of his traumatic childhood and lonely adulthood.
In The Wheel of Time, one of the attributes of the Aes Sedai/Warder bond (and it's variations) gives those involved the ability to sense each other's emotions.
Also, when channelers enter into a circle together they can feel the others involved to a certain degree.
Trapped on Draconica: Erowin can sense and influence the feelings of others, which she uses to calm wild animals and sense hostile intent.
The sequel, Legacy of the Dragokin has a contrasting example: Mordak can manipulate others because he learned empathy from living inside human minds.
Cammon of the Twelve Houses series is a very cool and effective version of this trope. His powers enable him to act as a Living Lie Detector, and not only read others’ emotions but influence them. He can also sense the presence of other people nearby. He also is not prone to crypticness or vagueness—though he can sometimes tends to forget that everyone else can't sense what he does and fail to pass on valuable information.
Molly Carpenter of The Dresden Files evolves into this as she becomes more proficient with magic. Her skillset is very powerful; unfortunately, to use it against a person, she must go inside that person's mind and feel what they feel. When fighting criminals and Eldritch Abominations, for example, her mental stability is adversely affected.
Counselor Deanna Troi from Star Trek: The Next Generation is the archetype in most SF fans' minds. note At least one Empath appeared in Star Trek: The Original Series. Thus, she is the reason many of them think the empath is useless. Aliens could be invading the ship and she would say something like "I sense danger". This was lampshaded by her mother Lwaxana, who is an actual telepath of considerable ability. In the episode "Manhunt", Lwaxana expresses astonishment that nobody else noticed that two alien "ambassadors" were actually assassins whose robes were laden with hidden explosives.
There is also a rare example of a male Empath in the TNG episode "Tin Man" with Tam Elbrun (Harry Groener, the Mayor in Buffy), although in his case he is actually a telepath so sensitive that he cannot block out the thoughts of everyone anywhere near him (even on other starships) that boards an alien life-form to get away from everybody else.
In the episode "The Perfect Mate" there is an "empathic metamorph" whose powers tell her exactly what others would find sexually attractive. It's stated that this ability occurs more often in males of her species but we are not shown an example.
Vulcan telepathy can also double as empathy, but both are limited to physical contact. (With the exception of bonded couples.)
This is River's power in Firefly.It's unusually effective as she uses it to see things she can't possibly know, but her unstable psyche means they come out as what sounds like stereotypical crazy, symbolic phrases. Also she can sense thoughts directly, which leads to the plot of Serenity.
In later seasons, Phoebe in Charmed developed the abilities of an empath in addition to being able to see disjointed images of the future. This is one of the few times that a person with such abilities is referred to as an empath. Her powers were slightly cooler than normal empaths as all magic in Charmed is linked to emotions; control of emotions allows you to control other people's powers.
There was a more dangerous version featured in an earlier episode. Thinking they were saving an innocent, they transferred empathy from a demon to Prue, only to find out she was feeling all the emotions, and the demon was being punished with it.
There was also one rather Squick moment where Phoebe realized that a guy they were talking to was having erotic thoughts about her sister and, due to her powers, she was too. Cue Phoebe running out of the room.
Peter Petrelli of Heroes is described by another character as an "empath," but this appears to refer to his ability to reproduce other characters' powers (nominally by recalling his emotional reaction/connection to those characters, though this has not yet been explored in depth), rather than directly psionically sensing their emotions or mental state.
Matt Parkman is a much straighter version of this trope, as his power allows him to read the surface thoughts of nearby people, dig deeper into their minds to read the secrets they're actively trying to hide, and ultimately, to create realistic dreamscapes and trap people in them. As one character has said, "Anything the mind controls, you control".
Lydia's empathy manifests as tattoos linked to what the person is feeling.
Teyla, The Chick from Stargate Atlantis, has a cross between empathy and telepathy. The twist is that she can only sense the Wraith (the Big Bads) with this power. This is subverted in that it does not lead to fainting spells, but rather to awesome asskicking when her power allows her to get possessed by the Wraith. A notable season 1 episode features her going berserk and flooring the whole team with an IV stand in the infirmary.
Babylon 5 had a much better version of the traditional empath; instead of emotion sense a la downgraded telepathy, he had emotion manipulation a la downgraded mind control. It didn't work out very well for him, but running willy-nilly with the power on Garibaldi's watch was a bad idea.
Raw, the "Cowardly Lion" analogue in Tin Man is a pretty powerful one of these, with clairvoyance as a "side." Also an Empathic Healer.
Both Stark and Zhaan from Farscape had this to varying degrees and applications. Stark used his abilities to ease the passage of a person's life from this world to the next and since he was part of a slave race he had to do this quite a lot. Left him a bit weepy, cringing, and fatalistic. Zhaan had this and other abilities from her training as a Pa'au priestess and while it would sometimes cause her some pain she had an underlying core of tranquility to keep her strong.
Lorne, whose empathic abilities came out when people sang. His future telling skills were about as reliable as a cheap fortune cookie though.
Also the demon Barney in "Parting Gifts".
Illyria can sense (and is disgusted by) Wesley's grief. In later episodes she also senses his desire for her when she takes Fred's form, and calls him on it when he rejects the idea of sleeping with Fred!Illyria.
Hannibal: Will Graham is a rare non-psychic example. His gift of "pure empathy" allows him to get into the minds of the criminals he hunts and causes him many troubles along the way.
Wire in the Blood has Dr. Tony Hill, who basically becomes the killers by seeing and understanding how they think and feel. He can't fight for crap but uses his weaponized empathy to save himself time and again when he inevitably attracts stalkers. Which he does. A lot.
In Doctor Who, the Doctor seems to have some form of this power along with his telepathy, although pure receptive empathy is only explicitly used by the Ninth Doctor. It's implied that it's a normal sense for Time Lords to have (apparently the Master is disabled in this regard). Given the Doctor's often oblivious behaviour, one assumes that he normally blocks his empathic perception, perhaps out of respect for his companions' privacy.
The Doctor: Can't you sense it?
Jack: Sense what?
The Doctor: Coming out of the walls, can't you feel it?!
Rose and Jack: ...
The Doctor: Funny little human brains. How do you get around in those things?
The Doctor: It's afraid. Terribly afraid. And powerful. It doesn't know it yet - but it will do.
A more realistic version appears in one of the last 11th Doctor episodes, a woman who is good at picking up on the emotions of those around her, feels more deeply than the average person, and possesses plot-important but very mild psychic abilities. The Doctor notes that empaths are often the most compassionate people in the world, but also often the most lonely.
The hobbit-like kithkin in the Magic: The Gathering world of Lorwyn are a race of friendly country-dwellers with an empathic bond to each other called thoughtweft.
Shadowrun gives this ability to Adepts, called Empathic Sense. However, because of the system, it's near-universal for an Adept to possess other, more useful abilities as well.
Borderline universal for psykers in Warhammer 40,000. Almost all of them have far more powerful abilities as well.
The Elohim, an angelic choir from In Nomine, can not only sense a person emotions, but can determine why they feel the way they feel and determine how they'll react to any given situation.
In the Ravenloft setting, fallen paladin Elena Faith-hold was Blessed with Suck by the Dark Powers, who took her former Detect Evil class ability and made it detect strong emotions directed at her instead. The self-deluded darklord now registers others' hatred, fear, or love for her as "Evil", and smacks them accordingly.
The race of Muses in the Talislanta setting are strongly empathic, so much so that they prefer to let little fairy-type critters called "whisps" translate their desires into speech rather than talk out loud. Muses can also become Emotion Bombs or even project hallucinations into others' minds in a pinch, though they keep quiet about these powers because they're peaceful and hate using them.
A minor advantage in GURPS that works only on people. Other versions work on Spirits, Animals and Plants. The most important effect is that even creatures who are normally immune to manipulation can be convinced of things by a person with the appropriate Empathy power.
Gamma World had an interesting twist on the idea: "Badders" (a race of humanoid badgers) were all empaths...and complete jerkasses on account of having to put up with the bad vibes of other badders all the time.
Dungeons & Dragons has the Argent class - Psionic characters that can manipulate the emotions of both their enemies and their allies. Most of their attacks either boost their allie's stats or degrade their enemies. This class, in the role-playing sections, are either played as larger than life, feeling their emotions more powerfully than normal and being influenced by/influencing their environment...or, as a twist, to be the Stoic who always tries to keep their emotions in. The rule book makes a point to mention that while playing them as loud, emotional types is okay, you have to be careful not to turn them into a caricature.
In Fate/hollow ataraxia, the character Caren Ortensia was born with the ability to "feel" demons, which in Nasuverse are phenomena that (try to) take away pain from humans. Whenever anyone does something bad or hurtful near her, she feels the pain equally. In the most extreme case, giant spikes erupt from her body if Avenger even approaches her (which is why she's always covered in bandages).
Averted (or something) in City of Heroes, where Empathy just means Healing.
Using health as Liquid Assets shows up in their Absorb Pain ability, which is the strongest heal in the game but damages the caster. It's the only true empath-style power, though.
Neku from The World Ends with You...the very last person one would expect to wield such a power, given that he really doesn't like people.
The Liir and the Zuul from Sword of the Stars. The former are a species of pacifistic dolphin telepaths to whom the concept of violence is abominable, because they feel the pain of everyone hurt around them. The latter are a species of telepaths who like feeling other people's pain, and delight in causing as much of it as possible. It goes without saying that the two really don't get along (even when we don't take into account their history).
The Liir's empathy is so strong that they consider everyone in their military to be sociopaths, and even then the suicide rate among Black Swimmers is high.
In the sequel a faction of Zuul ally themselves with the Liir, they adapt their mind-ripping ability to psychotherapy.
The Suul'Ka sociopathic Liir elders who enslaved the others so they could cheat death are even worse than the Zuul. They actively reject empathy as a weakness. Their empathy is even stronger than the average Liir's empathy and they still don't care about the suffering of their victims.
Deconstructed with FEAR's Alma, who was highly sensitive to the emotions of those around her - and the strongest emotions were negative ones, which rapidly proceeded to drive her completely insane.
In Pokémon both Ralts (the Feeling Pokemon) and its evolution, Kirlia (the Emotion Pokemon) are empaths. They can sense people's emotions with their horns and usually take on the emotion their trainer is feeling. If Ralts sense hostility in the area, it will hide immediately. If Kirlia have positive trainers, their attacks grow stronger and they even become more beautiful than normal Kirlia.
Their abilities reflect this within the actual game mechanics as well. Trace copies their opponent's ability, and Synchronize will inflict their opponent with a status effect that they're affected by.
Galaxy Angel: Mint Blancmanche and the entire Blancmanche family. Her father has used it to become incredibly wealthy, so much so that the enemy doesn't attack Blancmanche ships probably in fear of destroying the economy.
DLC character Javik in Mass Effect 3. He can read the emotions left over in an area inhabited by an individual, and by touching someone, he can determine their personality, merits and flaws within seconds.
In Koi To Senkyo To Chocolate, one character can perceive other people's emotions as colors. The protagonist theorizes that she developed this ability as a means of surviving her abusive surroundings as a small child. She's also the only powered character, as the setting is otherwise realistic.
In Metanoia it was recently revealed that main character Star is an empath, which makes the fact that he worked as a (very efficient) assassin even worse, or as one character put it upon realizing this: "He dies with them. Every murder is a suicide."
Faen from the Sullisin'rune clan in Drowtales are Empaths, and known for going mad as a result. Besides healing and sensing/projecting emotions Faen turned a teacher into a vegetable mentally and seriously wounded another student when she had a freakout that lead to her running away to the surface. She also turned a an already dangerous, battle-trained direwolf into a berserker thanks to an emotional feedback loop of fear (from her) and anger (from the wolf), apparently instinctively, in a fit of Power Incontinence.
Her mother Ash'waren is the same, only with control over her powers and about 1000 years of experience. Due to prejudices against dark elves, she does a masquerade and use her Empathy to disguise herself as a drowolath, an illusion she have no problem to uphold in front of a council of great and small clans of the city they live in, a crowded market and her own clan. Exactly how powerful she is is not known, and if Faen's freakout is any indication, nobody wants to find out. It was mentioned by the creators in a podcast that if she doesn't shield her emotions, her mood might affect everyone living inside the Sullissin'rune clan's town sized dome. Did we mention that she has the Drowtales version of Temujin/Ghenghis Khan more or less wrapped around her little finger?
Parodied in Starslip. Raquel turns out to have this ability due to being a telepathic Quel, but when she started doing Troi's "I'm sensing emotions" schtick, she had to clarify that it wasn't the emotions of the people they were talking to, and in fact she cannot sense emotions behind the room she's in.
Uryuom (and greater chimera) from El Goonish Shive have empathic abilities they use instead of pheromones, as well as low-grade telepathy. Both are related to antennae.
Kili of The Dragon Doctors is a shaman who doubles as a therapist (not far off from Deanna Troi of TNG) and does possess certain empathic abilities. As a full-fledged shaman, though, she possesses a lot more tricks than merely stating the obvious emotional state of someone.
In Dan and Mab's Furry Adventures Cubi can sense emotions, as they comprise their diet. It's often a disadvantage in combat, but not for the usual reason, rather they get blinded by the emotions and fight like drunkards.
In Genocide Man Giri's tribe of genetically engineered blonde Eskimos have a non-psychic version, they are very good at reading subtle body cues to the point where they can practically read minds, and manipulating others. When Jacob comes to wipe them out they convince him to spare them, and push him over the edge to suicide, though Giri is trying to change his mind on that bit.
Any, of M9 Girls! can read emotions and, when she concentrates enough, have an incipient telepathy. She can be blocked from reading very deep emotions, however.
Plus the mutant whose codename is Frank. He's a boy whose only powers are receptive and projective empathy. But he's really, really powerful and he can't turn it off.
Phobos and Deimos also have a VERY sucky version of this, as they scare the crap out of people with their fear aura, and have to feel that fear, which makes them go a bit overboard with power...
From the Global Guardians PBEM Universe: Sweet Sorrow is an empathic emotion manipulator who concentrates on the darker emotions. She can sense the full range of human emotions quite accurately, and is very good at sparking the darker range in others.
Chakats have innate empathic abilities. Some, mostly those with a Skunktaur parent, have other Psychic Powers.
The Protege in Brennus is the only known 'sympathetic empath', able to interact with people piloting remote-controlled equipment in his range, regardless of their actual distance.
The Passion Path of Magic, from The Saint, allows a mage to feel other peoples emotions. When combined with the Connection Path of Magic a mage can heavily influence what others think and feel.
Obscurus Lupa reviewing Charmed becomes infuriated by Phoebe's empathic abilities, because Phoebe is a Charmed One and incapable of actual empathy. All giving her empathic abilities does is give her license to complain about other people's problems as though they were her own problems, which she will do, loudly and obnoxiously, to the face of those people.