In Bleach, Ichigo's powers are first activated at the beginning when Rukia decides to share with him a portion of hers, although Ichigo accidentally sucks up more than she was willing to give. Ichigo's powerful aura ends up activating the dormant spiritual powers of Sado and Orihime. Because of the nature of quincy powers, Uryuu can suck up Ichigo's power when touching him.
It's also stated that other Soul Reapers are able to do this, but the practice of doing so is illegal. Rukia only empowered Ichigo as it was either that, or die.
The Emperor of the Vandenreich and the progenitor of all Quincies can empower others by lending them fragments of his own soul. The elite of the Vandenreich boast a variety of superpowers as a result. Heat manipulation, lightning, Super Strength, and reality warping are a few examples. Emphasis on "lending". The Emperor eventually takes back what he gave, with interest.
CC (and VV) from Code Geass can bestow Geass abilities to people, as she did with Lelouch.
Calumon, also known as the Catalyst from Digimon Tamers is a type 3, able to make other Digimon Digivolve with his Shining Digivolution ability. The Digi-Destined/Chosen Children in all of the seasons are also examples of type 3 to their Digimon partners.
The protagonist of Tende Freeze is a type 3. The twist is that he's unaware of his ability.
Wizards in Negima! are Type 1, able to grant magical transformations or artifacts to others via Pactios.
Under the right circumstances, Yellow can (sub)consciously boost her normally weak Pokemon's levels to the eighties by spirit alone, but this has the unfortunate side effect of her forcing herself to sleep off the strain very soon after.
The Tailed Beasts in Naruto grant special abilities to their hosts. The titular character carries the Kyuubi (9-tailed fox), which grants him an almost bottomless well of chakra to draw from.
Naruto eventually figures out how to imbue others with the Kyuubi's power he proceeds to empower an entire army.
In the anime of Haruhi Suzumiya, Yuki (and the other)'s speech about Kyon being normal and them having powers trips this tropers' sense of Type 1 of this.
The titular character is said to have empowered epsers like Koizumi through altering the very structure of reality. Possibly a variant of Type 5 since the power granters own abilities remain unaffected.
In the Anime adaptation of the Darkstalkers series, Anita has the ability to heal Donovan's wounds, as well as giving him a power boost that enabled him to destroy the previously unstoppable Pyron. She only does this when he's at the brink of death though, because it's activated by intense emotional stress.
Type 3 happens at the end of every single season/arc/movie of Saint Seiya, usually with the titular character or Athena herself receiving the Cosmo of the remaining four Bronze Saints so he or she can deliver the final blow to their ultimate foe. In the Sanctuary arc, Athena would also lend her power to her Saints to overcome particularly troublesome enemies.
Ajimu from Medaka Box has the ability to give her Abnormal powers to other people. It doesn't weaken her at all since she has over a quadrillion Abnormalities to spare. Of course, one of her superpowers is the ability to count that high.
Her companion Hanten has the ability to create new powers from scratch and give them to others. He's only responsible for about a hundred of Ajimu's though.
Moka does a type 4 to Tsukune in Rosario + Vampire, granting him powers on par with true vampires. Of course, this comes with some nasty side-effects...
Something of this is implied in Tengen Toppa Gurren Lagann. At first, Simon is the only protagonist with Spiral Power at hand. But over time, the rest of the cast develop it as well, starting with obvious badasses like Kamina and Kittan, and moving all the way down to the Team Pet. Either Simon triggered Spiral Power growth in his companions, or he inspired them to awaken the power within themselves.
Kamina might be a subversion. It's never clear if he used Spiral Power at all. According to Word of God, he has the lowest potential for it among the main cast, and you never see Gurren use it without Lagann attached. Kamina's real contribution to the team was inspiring them to take action, rather than actually being worth anything in combat himself.
In K, the seven Kings are able to bestow their powers (as a form of either Type 1 or Type 2) onto ordinary people if they get accepted into their clans. However, they usually must first pass a test of some kind, which can be quite painful or risky if they fail. For example, to join the Red Clan known as HOMRA, a newcomer must shake hands with the Red King Mikoto Suoh while his hand is on fire and not get burned. Once they get accepted though, their powers appear to be permanent since a former member of HOMRA who later joined the Blue Clan is shown to possess both of the clans' powers.
Kagerou Days: The Mekakushi-Dan's eye-powers are eventually revealed to be a version of Type 1 from Azami, Mary's grandmother - an immortal Gorgeous Gorgon. After Mary and Shion died together on August 15th over a century ago, she ordered the Heat Haze to let them in, and gave Mary the Combining Eyes snake. Ever since, people who die in pairs on that date (Kido and her sister, Momo and her father, Hibiya and Hiyori...) enter in that pattern, one being left behind and the other coming back with one of the snakes inside them.
The wizard Shazam granted teenage Billy Batson the ability to transform into Captain Marvel, an adult superhero (with Billy's mind in control) wielding the power of 2 gods, 2 demigods, a titan and a mortal with the wisdom of God, who had themselves given the Wizard their abilities to empower a champion to defend mankind.
Any bearer of the Power of Shazam can share their power with others, which is why there is a whole Marvel "family". Billy shared his powers with his sister Mary and his friend Freddy to turn them into Mary Marvel and Captain Marvel Junior respectively. Billy's Evil Counterpart Black Adam (who is empowered by a different set of deities) did the same thing with his brother-in-law Amon to turn him into Osiris. And then there's the Lieutenants Marvel, three guys who can do the Captain Marvel shtick because their civilian names happen to be "Billy Batson".
In Lucifer, the title character bequeaths his Lightbringer power to Mazikeen before setting off for the Void outside Creation.
Marvel Comics' Sage has the ability to "jump-start" other mutants. Initially this was depicted as the ability to activate the latent mutations of mutants who hadn't yet manifested, but at this point it's more or less an excuse to do whatever the current writer wants to do to another mutant's powers (for example: turning Beast from apelike to lion-like, and curing Gambit's blindness).
And one of the ever-diminishing supply of X-Men ex-Morlocks has the power to supercharge other people's powers by jumping into their bodies. This character is in limbo.
And of course, there's Sabra, the Israeli superheroine who can grant up to half of her own life-energy into someone else, enhancing their strength, speed, stamina, and occasionally giving them super-powers. She can also take that energy back... at least once, killing the subject because they hadn't healed from the wounds that were the reason she gave them her life energy in the first place (It's okay; they turned out to be a bad guy).
After losing his super-speed on M-Day, Quicksilver embedded mutation-inducing Terrigen crystals from the Inhumans into his own body, giving him the ability to restore lost mutant powers, albeit in an erratic and dangerously supercharged form.
Gambit and Rogue pull a Type 2 when Gambit dies in various continuities. Rogue keeps Gambit's powers for awhile, either trading in her original or keeping both. They never stick permanently(powers and death).
Apocalypse is fond of doing this for his four horsemen. He uses his Celestial tech to either supercharge their abilities(like when he made Gambit Death) or give them entirely new abilities (like when he made Angel into Death).
Fabian Cortez, one of the X-Men's foes, combined this with Restraining Bolt - he could both temporarily supercharge a mutant's abilities (potentially burning them out in the process) and temporarily surpress a mutant's powers. He could only do this by touch, however.
Redbeard from the Savage Dragon line of comic books granted random powers, from the stupid to the insanely dangerous.
The Big Bad of Seth Green's Freshmen has the ability to temporarily give others he touches superstrength and nigh invulnerability, but it has the same side-effects as taking mundane steroids.
Hal Jordan's power ring has the ability to produce power rings. Kyle uses a copy of Hal's Ring to distribute rings to John Stewart and Jade. Later, Hal tries to give Clark Kent a power ring near the end of a year Clark had spent being powerless.
When he loses his ring very early on in the comics, after saving the boy who'd found (and couldn't control) it we see him exchanging it for a created replica which did nothing but glow at will. For a young boy with friends, that's a different type of Super Empowerment.
Also in DC Comics, the titular device in Dial H For Hero is an old-fashioned telephone dial that can transform the user into a random superhero for a short period.
The shortlived DC series Touch (which focused on a world with superpowers but not superheroes) had as its main character a man who could give others superpowers.
The New Universe has the Star Brand; each user can pass the Brand on to anyone or anything else, while still retaining a portion of the power. (Passing it into an inanimate object is... not recommended.) And it is responsible for giving all the powers to all the Paranormals on Earth.
Valiant Comics' Harbingers were thought to be natural mutations. Turns out Reality Warper Solar is unconsciously responsible. And Sting and Harada both had the power to locate and activate latent Harbingers.
A company called the Power Broker sells superpowers. Generally those of a brick (superstrength, supertoughness).
There's also a drug called Mutant Growth Hormone or MGH, extracted from superhumans (not just Mutants) that bestows various temporary powers.
The "U-Men" group promises to provide its members with tissue and organ transplants that give them superpowers. The catch is, they have to go catch and kill mutants to get the samples. Yeah, the organisation that catches and kills mutants for power is offering to turn you into a mutant! That can't possibly go wrong...
Loki is famous for giving out powers as part of his Deal with the Devil schemes, but he actually holds up his end of the bargain. The God of Mischief actually never twists his words when giving out superpowers and he tends to let you keep them permanently, regardless of how successful his plan with you is.
Crusher Creel, "The Absorbing Man", was originally just a very muscular thug. Then Loki gave him the power to absorb physical properties from things he touched and let him keep the power even after he was no longer useful. Crusher owes his entire supervillain career to Loki's generosity.
The Wrecking Crew get their powers from their leader, the Wrecker. He has an enchanted crowbar that only he can control, which gives people Flying Brick superpowers. He and his crew/family of friends remain very loyal to one another. But he himself was just a street thug, until he got the enchanted crowbar given to him by Loki, who allowed him to keep it after another failed scheme.
Welcome to Neopolis! Hope you enjoy our many fine tourist attractions. But word to the wise, be careful, be safe! Many of the "working girls" here have S.T.O.R.M.S., a disease that can mutate you horribly. Yes, there are rumors that you could become a godlike being with vast powers, but don't believe it! It has been known to happen, but it's very rare. Don't take the chance! Visit the Neopolis Free Clinic today!
Christine Trelane from the Wildstorm Universe possesses the superpower to activate latent powers in humans and transform them into post-humans.
When powered by the light of a blue sun, Superman can grant temporary Kryptonian powers to others.
Mr. Negative from Spider-Man. Sometimes he just uses this to bring out latent abilities in people or bring their dark sides to the surface. Other times he flat out gives them powers like giving his mooks immortality.
Vartox can infuse people with a portion of his energy, giving them temporary powers like his.
In H-E-R-O, the HERO Dial not only turns its users into superheroes at random, it grants permanent powers if used enough. However, these powers have to be 'unlocked', and dial users are mostly unaware of them until they're placed in a situation such that they activate subconsciously.
In With Strings Attached, Paul gets his magic seemingly through the incompetence of As'taris, who tried to change him back to normal after he was turned into a diamond statue. Paul instead explodes and reforms with Super Strength and Nigh Invulnerability (and a few other things that pop up during the book). From what the Fans say, it was actually the meddling of the C'hovite gods that bestowed this power on Paul. But we later find out that Paul was the creation of Jeft, who used him to “test out some theories I had” and who got “a little overenthusiastic” with him.
The Dark World of the Pony POV Series has a couple examples of this. Liarjack, upon her Heel-Face Turn back into Applejack, gets an Element of Kindness from Apple Bloom's spirit; the act of giving it freely makes it split in half, giving them both an Element. She later repeats the process with her Element of Deceit (as does Rainbow Dash with her Element of Free Will), giving it to Rarity so she can now have ALL the Elements of Chaos at her disposal.
In A Great Endeavor, it turns out that ground-up unicorn horns can be snorted to grant humans magic. The Nazis make extensive use of these "warlocks", but it ultimately doesn't help stop the Allied tide.
Films — Animated
In Disney's Aladdin, Genie grants Jafar's second wish, to be a powerful sorcerer, but Jafar is tricked by Aladdin into making a third wish, which is to be a genie himself, which results in him getting sucked into a lamp and then thrown into the Cave of Wonders to "chill him out."
Films — Live-Action
TRON: "Sark, all my functions are now yours. Take him!" It's not altogether clear whether this is a type 1 (the MCP explicitly said "functions," which is a very big deal among Programs) or a type 3 (all Sark had time to do is grow gigantic and stomp around.)
Ivy from Xanth had the ability that could selectively supercharge people's properties, including their magical talents.
Her husband can do the same thing by canceling out magical properties, when they're turned back on the built up energy causes the powers to come back by multiple times.
Croyd "the Sleeper" Crenson temporarily spread the Wild Card Virus; his strain is different from the original as it can reinfect the already infected and affected, although keeping the original 90 dead / 9 jokers / 1 ace distribution. Among a few lucky individuals, Typhoid Croyd turned the joker Snotman into the ace Reflector. Croyd also infected Tachyon, who is now a latent carrier.
Several other Aces from later books and RPG scenarios can release the original strain of the Wild Card virus.
Damsel, a Type 3 female Ace. She can boost the powers of her designated "champion" (such as turning a levitator into a bona-fide human jet).
Cameo has this trope as her power's side effect. She can channel the memories of the dead from items they owned, and for items owned by an Ace with mind-driven powers, e.g. telekinetics, she also channels the power. The catch comes with telepatic Aces, as Cameo also channels their personality.
The Cyborg and the Sorcerers series by Lawrence Watt-Evans has sorcerers whose "magic" (Psychic Powers) originated from Mutants in an After the End colony world nuked back to the Dark Age. They learned how to psychokinetically alter other's neurons to pass on their powers, and by the time of the story, the only way to get magical power is from another wizard; the original gene has long since died out.
In the Ethshar series by the same author, this is also how the (psychic-type) magic of a warlock is passed on; the other dozen or so forms of magic are either inborn or trained for.
In Nina Kiriki Hoffman's book A Red Heart of Memories and its sequel, three of the characters were turned into powerful witches by a ghost who cursed them when they invaded the house he was haunting. However, the ghost was only able to do so because it was Halloween and the house itself(which is sentient and magical) wanted to welcome them and give them magical power.
The Orc king Obould Many-Arrows from the Forgotten Realms was blessed by the Orc god Gruumsh One-Eye through an ancient ritual that focused his entire tribe's prayers on him. Already a strong and cunning orc, Obould became a mighty warrior capable of defeating the frost giantess queen in single combat. Fortunately for the Realms, Obould ultimately became a PragmaticVisionary Villain more interested in founding a stable kingdom than in violent conquest.
In the Dresden Files, the Faerie Queens of Summer and Winter can transfer a portion of their powers to mortals to turn them into their Knights. The transfer is permanent and only death can free the power.
Witches in Septimus Heap have the power of Super Empowering with a kiss. Subverted however, since Jenna's gain in Darke is mostly the ability to disguise as a Darke Witch and to sense the Darke.
In Labyrinths of Echo Order Grand Magisters commonly shared their power among the order. Max also resurrects the tradition to share luck.
Tonino Montana of the Chrestomanci series has the unique ability to enhance any spell he takes part in, making it ridiculously strong. He's also been known to hijack enemy spells and turn them to his advantage.
Also D.L.'s mother, but only in the online comic books.
In addition, the combination of Mohinder's research, the formula that Kaito had been hiding, and the catalyst that Arthur Petrelli had robbed from Hiro in the past created a serum that could grant people artificial powers without adverse side effects.
In its fourth season, Danny Farrell in The 4400 gains the ability to mass produce Promicin and diffuse it in the air. Problem is, it has a 50% mortality rate, and he quickly creates an 'infection' effect where everyone in Seattle is exposed and would die or gain an ability. In the end, he's overwhelmed with the guilt of indirectly killing thousands, and since the only way to stop the spread of the Promicin was by putting him on an inhibitor which was slowly killing him, his brother Shawn is forced to kill him.
The Tok'ra in Stargate SG-1 grant their hosts a highly extended lifespan, perfect health, and access to their own memories, as well as letting them operate Goa'uld tech and sense the presence of Goa'uld in others. This "blending" is also voluntary, and the human is allowed to remain in the driver's seat, as opposed to the Grand Theft Me nature of the Goa'uld. Jacob Carter (Sam's dad) was cured of terminal cancer this way.
Rodney accidentally manipulated his own DNA structure resulting in him developing telepathic and telekinetic abilities, greatly enhanced intelligence and hearing, among others; all due to his brain becoming more active than that of an average human. Eventually his brain became so advanced that he was unable to keep himself alive if he doesn't ascend or find a way to turn himself back. Thankfully, Atlantis' medical department kept a DNA sample from everyone so they turned him back.
Weir became infected with Replicator cells but Rodney managed to shut them down before they took control. Later, she suffered brain injury so he reactivated them. She instantly gained super-healing and the ability to mentally tap into the Asurans' subspace network, stealing information and temporarily freezing other Replicators. When she became fully Replicator, she was able to stick her hand into another Replicator, making it fall apart to a pile of cells; prior to that, she was uploaded into subspace and essentially became an AI able to infect and control computers to an extent (she was so powerful that Atlantis' systems gone wacko from her presence until she rebuilt FRAn and possessed it).
Due to Teyla possessing Wraith genes, she has Wraith telepathic abilities as well as detecting their presence (hell, she mind controlled a Wraith queen). And maybe Chaya too but that's justified by the fact that she's an ascended Lantean in physical form.
An unintended type 5 due to the Lanteans interbreeding with humans. The result? The ability to control Lantean tech with the mind, also known as the ATA gene (Sheppard has a so powerful gene he doesn't need to concentrate at all); straight type 5 when Beckett managed to figure out how to imprint it artificially (he also has it naturally, so does O'Neill).
Jacob has the power to grant immortality (Richard) and possibly healing abilities (Locke, maybe Mikhail?)
And his powers as the protector of the island came from the crazy lady who claimed to be his mother, who passed them along (type 2) by having him drink water out of a cup she filled.Jacob later does this to Jack, who does it to Hugo. Who then makes Ben Linus his second-in-command.
Season 4 of Haven introduces two thugs who can leave a glowing hand print on people that only Audrey can see. People with this hand print on their bodies gain a Trouble or have their existing Trouble augmented.
Toa heroes in can unlock the latent Toa-energy in chosen Matoran by infusing them with their power, usually by giving them Toa Stones which they've previously powered-up with their own energies. If the Stones are activated, they transform the powerless Matoran into mighty Toa, but in turn depower the Toa who gave them the stones into a less powerful Turaga elder. So far, direct empowering hasn't been seen in the story.
Light Matoran, the only type of Matoran who have working powers, can grant Toa special light-based abilities as long as they're touching them.
Nuva Masks can extend their powers to those standing nearby. These powers only work as long as the original user continues to keep the mask active.
The GURPS advantage Affliction with the Advantage special enhancement gives the ability to temporarily give people powers, depending on the advantage in question.
And later supplements included the rules to remove the "temporary" part.
The Celestial Exalted receive their power from a shard of the Celestial Incarnae, the most powerful gods in the setting.
The Abyssals and Infernals receive their shards from Deathlords and the Yozi, respectively. They're still technically shards of the Unconquered Sun, but mutated and warped to connect the recipient to the Neverborn and Yozi, instead.
Furthermore, almost all forms of supernatural can learn charms to perform this role themselves, such as the Solars' 'Power Awarding Prana', which allows the target to use essence and Solar charms for as long as the Solar maintains the charm.
The Lunars can do similar thing. The recipient(s) eats a small Essence-filled chunk of the Lunar's flesh, and gains Awakened Essence mutation that allows them to learn and cast Sorcery, for as long as the Essence is committed. Given the sheer scope of things possible through Sorcery and the relatively cheap cost of committed Essence, a Lunar can potentially raise an army of mortal superheroes all by his or her own.
Though it depends on the setting, divine spellcasters in Dungeons & Dragons usually receive their powers from the gods.
Similarly, Warlocks gain their powers from consorting with strange otherworldly powers.
In Fourth Edition, Primal classes gain their powers from nature spirits.
Clerics can learn a spell known as Imbue With Spell Ability, enabling them to donate some of their other spells to the target, who can cast them at his own discretion. Necromancers in Forgotten Realms sometimes use similar 'Imbue Undead With Spell Ability' spell.
The Wish and Miracle spells can also enhance basic attributes by up to 5 points (which is quite a bit).
Planescape and Forgotten Realms as divine-heavy settings introduced special forms of empowering. Proxy is agent of a deity granted extra power and imbued with the divine will, that is not fully free-willed, but driven toward their god's agenda — not a big change, as they are picked from the most trusted servants; it's temporary, frequently for a specific task. Chosen is a being given a portion of the power significant on the deity's own scale — until willingly returned or lost in death; they're immortal and almost unkillable, in addition to hefty god-specific advantages. Seraph seems to be a specialized version of the Chosen (e.g. Hermes would make one a Seraph of thievery or commerce). Either is appliable to a priest or commoner, mortal or afterlife dweller or planar alike — it's a direct divine intervention.
It was indicated that the reason Mystra had so many Chosen running around was that she was so powerful that Ao told her she had to take measures to keep herself 'merely' a Greater God. Her solution was to put so many fragments of her power into various mortals that it made a significant dent in her power.
It has been suggested that sorcerers can be created by being at the right place at the right time...or being bathed in dragon blood as an infant.
Forgotten Realms also has the sarrukh, an entire specie with the ability to grant any ability to non-amphibian, living squamous. Any ability. They are also almost extinct.
The Changeling: The Lost and Vampire: The Masquerade gamelines have this happen to human PC's. In Changeling, humans who spend enough time in Arcadia become changelings either through eating the food there, surviving the abusive tasks of their keeper, or their keepers' magic changing them. They can also bestow minor blessing and sometimes even abilities to mortals through Pledges.Vampires do the whole embracing thing, as well as ghouling mortals with vampire blood. It doesn't kill them, but it does addict them and give them a small access to vampire powers and agelessness.
The Chaos gods from Warhammer 40,000 don't always turn their followers into horrible gibbering chaos spawn. Every now and then, they empower a few of them and turn them into incredibly powerful and nightmarish warriors. For instance, Kharn the Betrayer went from powerful Super Soldier to unstoppable bloodthirsty demigod after receiving Khorne's blessing. Kharn is now effectively the avatar of Khorne himself. And he's one of the tamer examples.
The Pokémon move Helping Hand does nothing but multiply the other Mon's Attack and Special Attack strength by 1.5 for one turn. Only works in Double and Triple Battles.
Eleven Pokémon have the abilities Plus and Minus, which raise the Special Attack of others with Plus or Minus. Similarly, Victini's Victory Star ability raises teammates' accuracy.
There are whole Metagame strategies that center around setting up powerful buffs, then passing them on to another party member using Baton Pass. Moves like Wish and Light Screen/Reflect also remain in play after the Pokemon that used them switches out.
The Naaru in the Warcraft universe can bestow the powers of the Light on mortals. And they can also be taken from them, forcefully, as the Blood Elves did.
As it's been revealed that was a plan on the Naaru's part to give the Blood Elves more of a connection to the Light than their offworld leaders desired, we're no longer positive about the latter.
The leaders of the Burning Legion are also capable of granting powers, though in a somewhat ruthless way. Sargeras gave Illidan the ability to see magic by replacing his eyes by a sort of magical smoke. This forced him to wear his iconic blindfold because the sight is somewhat unnerving to others.
In Chrono Trigger, Spekkio can unlock the latent magical powers of the descendants of Zeal. He can't technically grant them though, as demonstrated by Ayla (who was born millions of years before Zeal), Robo (who, as a robot, is not genetically descended from humans), and Magus (whose powers aren't exactly latent anymore).
To empower or not to empower yourself with Gig's power in Soul Nomad forms the bulk of the story.
Princess Peach can do a variant of this, producing items for Mario and Luigi in certain games.
Dancers and similiar classes in Fire Emblem are pretty much defined by their ability to do this. They can allow an ally to take another turn or, depending on the game, empower them for a short time.
Awakening allows a skilled enough Dancer to do both. Level your Dancer enough, and Dance not only revitalizes them but also gives them a surge of stats.
Pharaohs do this to buildings in Age of Mythology. If they target a resource building, workers delivering to it also work faster.
To rein in Ares' Roaring Rampage of Revenge in God of War, the gods grant Kratos some of their signature powers, culminating with making him the next God of War. In the sequel, it turns out that Kratos is too good at his job. To help Kratos with hisRoaring Rampage of Revenge, the Titans grant Kratos some of their powers. Then in the third and final game with the Olympians and Titans after him, the spirits of his fellow Spartans empower Kratos.
Grahf from Xenogears is an evil version, giving power to sufficiently angry, revenge-minded individuals and turning them and their mecha into super-powerful monsters.
Just before the Final Boss of Final Fantasy IX, after the party is wiped out by Kuja's self-destructive tantrum, you get to choose which party members to take into the Final Battle with Necron. The remaining ones will then surrender their life energies to resuscitate the chosen ones, in reference to a similar scene from Final Fantasy IV.
The Beast from inFAMOUS has the power to awaken the powers of everyone who has the conduit gene, supercharge the already existing powers of conduits and transfer all of his own power to another conduit. The last part is a one time deal though and ends with his death and Cole becoming the nex Beast.
Persona 4: Izanami-no-Mikoto empowers the main character and certain two others with a more flexible form of Persona. The result... isn't pretty.
Only the main character gets the flexible persona ability, due an already latent wild card trait of his(and a few clues in the game could be interpreted as Philemon having a hand in it behind the scenes).
Final Fantasy Tactics: The Zodiac Stones empower people who possess strong wish. Unfortunately, more often than not this turn those people into Lucavi demons.
Final Fantasy VIII: The main characters admit that they will be too puny to fight were it not for their Guardian Forces, which allow them to use Magic and fight on par with the Sorceresses. The price of this power isn't exactly cheap.
Final Fantasy XIII: The fal'cie is a particularly malevolent version of a Super Empowering entity. Sure, you get nifty powers, but it's all downhill from there even if you do what they say. Especially if you do what they say.
The second Knights of the Old Republic is almost built around this and a Deconstructor Fleet of the Star Wars universe. As the de-powered Exile, you are "re-awakened" by Kreia. Then, as you gather party members, they can often teach you skills or status buffs. Topping that, most of your party turns out to be untrained Force Sensitives. Gather enough influence with them, and the Exile can "awaken" then into Jedi (or Sith).
In the RPG-themed Adventurers!, Karn gains a Super Mode near the end of the "game", giving him several new moves. One of these moves is Truth Buster, which enables him to give his other party members their own super forms.
Coyote in Gunnerkrigg Court can do this easily, since he's a Physical God. But since he's a trickster god, the powers are often less than ideal. He gave Renard his Grand Theft Me power, but "for some reason," when Renard leaves a body, it immediately dies. He also gave Ysengrin his tree-manipulating powers, at great cost to Ysengrin's physical health and sanity.
In the Whateley Universe, Bill Wilson becomes Super Empowered when a millennia-old spirit gives him its powers, turning him into Tennyo.
In Worm, Othala can temporarily grant any one of a selection of superpowers to people by touching them.
Teacher has the power to grant limited forms of Super Intelligence and tinker abilities to chosen volunteers. This however comes at the expense of their free will for the duration.
A member of the Yŕngbǎn, a Chinese military unit of parahumans, has the ability split other people's powers among a group at a reduced degree, so every member of the Yŕngbǎn has a weaker version of the powers of every other member.
Aegis from the ASH universe can borrow other people's powers. As a side-effect, he also amplifies theirs, eventually to the point where their powers go out of control and, if he pushes it too far, even kill them.
In an episode of Static Shock, there was an old man whose superpower was to temporarily give others random superpowers. Unfortunately, it resulted in a druglike addiction, causing a Does This Remind You of Anything? type Aesop for Richie.
Static himself was a minor example, as it was secondhand exposure to the Bang Baby gas residue on him that gave Richie his permanent Gadgeteer Genius power.
In The Legend of Korra, we find out the origins of Bending. It used to be that lion turtles would grant humans various bending arts via energybending, something that could only happen one at a time because humans couldn't handle the stress of multiple bending arts. Wan, the first Avatar, managed to do so thanks to him merging his soul with a once-powerful spirit.