This actually becomes a plot point near the end of the main story, as Hokuto Shinken's ultimate technique, Musou Tensei, can only be used by those who know sadness, which in the story is tied to love.
Raou attempted to take a shortcut on that — thus letting him stay a "Bruiser with a Hard Center" — by killing the woman that Kenshirou loved, intending for the act to impart knowledge of sadness and love onto him. Thank gosh he was interrupted by her coughing.
Finding out that Yuria is dying BECAME the shortcut.
Bleach: Chad is so tough, he was Made of Iron long before his powers manifested into Super Strength. As a young child, he used to be a bully, until his grandfather corrected his behaviour into someone who uses their great strength to protect. Now he has no trouble admitting he's a tough, physical fighter who won't hurt a fly, and he's not afraid to cuddle soft toys in public... much to Kon's chagrin.
Heiwajima Shizuo in Durarara!! is universally accepted as the strongest man in Ikebukuro, described at one point as "violence in human form," but he's actually a quiet sort who dislikes violence and hates his own hair-trigger temper, and doesn't want to hurt anyone (except for Izaya).
Edward Newgate, aka Whitebeard from One Piece. An absolutely enormous man of incredible power and impossible toughness. When he is stabbed by a turncoat subordinate, he looks for a moment like he's about to reach out with his massive hands and rip the man apart. Instead, he kneels down and gives a tender hug to the much smaller man, and forgives him for his foolishness.
Sha Gojyo from Saiyuki. Foul-mouthed, skirt-chasing, iron-pumping bundle of muscle and bravado who is an absolute pushover for lost kittens, frightened kids having been an abused child himself, and women with hard-luck stories. It's stated that women in tears remind him of his stepmother, but beyond that, he's just a kind-hearted guy.
In a flashback story in Reload, he agrees to be held hostage in exchange for an old friend he knows perfectly well is just going to run out on him, because he has to give the guy a chance. After rescuing him, an amused Hakkai comments: "You make a terrible villain."
Uozumi Jun from Slam Dunk. He may be a hot-blooded trash talker on the court, but he breaks into tears when he realizes he can't play basketball with his team anymore.
Pokémon: Dawn's Mamoswine in the "Diamond and Pearl" anime series is all about this once he reaches his final stage. He acts all gruff, ignores his trainer for a while, and becomes The Berserker when angered (or when Dawn denies him/is short on Poffins). Yet he's definitely caring and protective towards his trainer and friends (especially after mellowing out), becomes putty whenever food is in question, and steadily shows fascination with Contests. Yet true to being of the emotionally repressed variety, he tries (initially) to deny all this.
The Ever-Lovin' Blue-Eyed Thing of Fantastic Four fame is very gentle and delicate with his love, Alicia.
The Thing is also like this to practically every kid that thinks he's the coolest hero.
Especially with kids who think he's cooler than the Human Torch.
The Thing also has a special place in the Marvel superhero community as possibly the most widely befriended hero ever, much like Superman or Nightwing from DC.
We have Marv, from Sin City, whose entire story gets kicked off when a hooker showed him some love and kindness and gets murdered, causing him to go on a quest of revenge. This man can snap you in half with his bare hands.
Notably, one of SHIELD's plans to calm him down is putting him in the same room with a bunch of puppies.
Marvel gods Thor and Hercules can fall in here too. Thor has a huge soft spot for children in one of his newest series, he goes to a faevala in Rio to give the impoverished kids a hearty meal of space melons, elf chocolate and a haunch of roast dragon. As for Hercules, he deeply loves his cuddle toy Amadeus Cho, even tearfully admitting that he murdered his wife and children out of jealousy (not madness like the myths depict) in order to convince Amadeus to go down an ultimately self-destructive vendetta. Hercules also loves striking friendships with fellow immortals because it hurts him deeply to have to keep watching his mortal friends die off.
Strong Guy of X-Factor - in a session with Doc Samson he reveals that his wit and banter are how he copes with tremendous, constant pain, both emotional and physical.
Films — Animated
Vlad the brawny vulture from Horton Hears a Who! is tough and evil. It's not true love in his case that brings on the tears; it's being touched by Horton's noble defense of the Whos and his forgiveness of the Sour Kangaroo.
Big blue scaremaster Sully of Monsters, Inc. has a soft spot for Boo, falling in love with her when most of his kind have been taught to regard small children with terror.
The Incredibles: Robert "Bob" Parr aka Mr. Incredible is tough as nails against anything Syndrome can throw at him except the possibility of losing his family. The mere thought reduces him to being barely able to speak.
Young MacGuffin from Brave is a gigantic bruiser who can break a hunk of wood with his bare hands and uses a bench as a weapon during a Ballroom Blitz. He's also a very sensitive guy who only wants to impress his dad. In the scene where it seems Elinor has lost her mind to the spell that turned her into a bear, he's visibly and earnestly weeping.
Wreck-It Ralph, from the movie, Wreck-It Ralph, is nine feet tall, weighs 643 pounds, and demolishes a brick building with his fists for a living. And he pretty much becomes a surrogate father to Vanellope, who just melts his heart.
Films — Live-Action
Sonny from The Godfather, despite being known for his explosive temper, is a loving if unfaithful husband and father who cares about his family and friends deeply.
And, of course, there's the "Friend To All Children" himself, Gamera.
Hellboy: a massive red demon with a huge stone hand prophesied to bring Armageddon... a big softie who absolutely loves kittens and will fight monsters to protect them.
TRON is a very sweet guy, despite being the biggest Badass in Cyberspace. He is visibly shaken and upset when he thinks that Flynn and Ram were killed, and hangs his head sadly when informed He Didn't Make It. With an urgent call from Alan at stake, what does he do? He goes to find and free Yori (and if you factor in that Deleted Scene, have a "private" moment back at her home). In the sequel? Twenty years of brainwashing is overridden with The Power of Friendship. And his Kingdom Hearts version celebrated the team's victory with hugs all around.
Daniel Craig's incarnation of James Bond. Cynical, ruthless, doesn't give a damn whether his martini's shaken or stirred (at first, anyway)...and he's also a clear-cut Broken Ace.
Bruce from the CHERUB Series; although he seems to be a hardcore martial arts fan with a thing for blood and gore, he still goes to bed with his little blue teddy.
Great, lumbering Rubeus Hagrid from Harry Potter is more soft spot than bruiser unless you make him mad, in which case the ratio switches over.
Project NRI has Scarlach "Carl" Platzchen, the muscular, 17-year-old, cookie-baking teenager.
“Who...” The room was dead silent. He opened up his suitcase. Everybody dreaded what he was intending to pull out. He yanked the item out, and the crowd simultaneously winced at the action. It was... a bag of homemade cookies. “...wants cookies?”
In Oz, no one fits this like Nick "the Tin Man" Chopper. He was cursed to become tin because he was determined to earn enough money to support his fiancee and get her away from the Wicked Witch. He rusted himself crying over crushing an innocent insect. Threaten harm to an innocent or to one of his True Companions? The axe comes out, and he becomes the scariest fighter in the land.
Bagheera in The Jungle Book is feared more than Shere Khan in the jungle, but he loves Mowgli dearly, even more than Baloo does. (The Disney movies invert these roles.)
Frankenstein's monster in Frankenstein is hinted to be this: all he wants to do is love humans. However, since everyone views him as a grotesque, hulking monster, everyone is scared of him and either runs away or attacks him on sight. When he hides in the shed of a family for several chapters he explains that he feels love and compassion for them; too bad that when he reveals himself to the family, they immediately attack him and drive him away. Over the course of the book, he begins to hate all humans, but still ambivalently wishes to help them, such as when he saves a girl from drowning in a stream.
Caldris in Red Seas Under Red Skies has been through several wars and will kill you for even mentioning Camorr. Just don't come between him and the kitten he keeps around "just for luck."
Skeeter Traps from Chronicles Of Magic is a tough, bloodthirsty little girl with a disturbing love of guns. However, she is also the one who is most willing to sacrifice her life for complete strangers and even cries when she believes her new friend has been killed.
Live Action TV
Angel: Ah, Angel. Brooding, angsty vampire trying to fight the good fight, within LA and himself. Who'd ever think that he dug Mandy and Barry Manilow, or had a fear of dancing (yet a secret desire to, despite how awful he is at it)? Or, y'know, go on about how much he loves Buffy when pretending to be drunk?
D'Argo from Farscape. He generally has two moods, angry and weepy.
Spike from Buffy the Vampire Slayer immediately establishes himself as this. He comes crashing into town with a bad reputation and a badass flair, shows up at the lair of the Anointed One offering to kill the Slayer... then looks on with concern and goes to wait on his Ill Girl girlfriend when she tries to come in with him.
Coach Shannon Beiste from Glee is a rare female example.
Dean Winchester from Supernatural. He may swear like a sailor, go hard on the liquor and sex, and be able to take on monsters and psychos with little problem, but he's got a soft spot for kids, his family, and Castiel. In addition, the character Tiny, a very large prisoner who is sensitive because of an abusive father, is seen in the episode "Folsom Prison Blues" (S02, Ep19) of Supernatural.
Like his tin counterpart, Wyatt Cain from Tin Man crosses this with Heartbroken Badass. The man is a scary-good fighter both in hand to hand and with his pistol, but his cold facade breaks down in a hurry when asked to do the honorable thing, or when he senses someone needs protection. At the end, he is almost on the verge of tears warning DG that she will have to face her sister alone.
He doesn't get a lot of fleshing out, but the hulking, muscular Sir Percival is quite a sweetie. This is epitomized when he risks his life to save three children.
Seth from 9 Chickweed Lane is a ballet dancer who looks like a linebacker but is a low key gay man and a hopeless romantic who went to some effort to get Edda and Amos together.
Duringhis face days, he also gave his hat to someone on the way out to the ring. That someone is typically either a kid there because of the Make-A-Wish foundation, or a member of the U.S. armed forces, who the WWE shows appreciation for by giving them seats near the action.
Sig from Jak and Daxter, at the end of Jak II, reminiscing about his childhood:
Also, despite the fact that he has a $9,999,999 bounty on his head for murder and dismemberment of anything that moves, he just adores puppies
Between the events of the first and second games, Hyperion forces capture him with the help of a traitor. According to the "Sheriff" who caught him, he broke down sobbing after she killed his puppy... before breaking loose and brutally murdering the traitor with his bare hands.
In Dragon Age: Origins, Leliana often comments that Sten is a 'softy' as she finds him picking flowers (which he excuses as 'medicinal') and playing with a kitten (he claims he was training it), although this is never seen by the player. He also comments about how great cookies are.
BioWare has a long and lovely tradition of these guys. Just check out Minsc. BIG guy, scary in a battle situation...turns into absolute mush when it comes to his beloved hamster. There's also Zaalbar. Two meters and change of walking fur and empty stomach that's a surprisingly sweet guy, and right behind his little Twi'lek buddy when it comes to sticking up for you after The Reveal. Shame on you Dark Side players!
Aveline takes this role in Dragon Age II. She's the toughest guard captain Kirkwall has ever seen, but has a tendency to melt when Donnic is in the same room.
Wrex in the Mass Effect series is mostly angry and bitingly sarcastic, but he does have the occasional emotional moment (the end of his personal quest in the first game and his reunion with Shepard in the second, especially). The latter moment is rather like The Eeyore going Squee. By 3, if you've done everything you can to work with him, he is incredibly happy to tell you that even if everything goes to hell and the genophage cure doesn't work, he considers you a blood-sibling and will make sure that every krogan for the rest of time knows your name.
Wrex: SHEPARD! MY FRIEND!
Jack in Mass Effect 2 is a prime example. If she makes it to the third game, she starts teaching a squad of biotic students at Grissom Academy. Then Cerberus tries to kidnap them. Bigmistake.
Heck, Renegade!Shepard him/herself has got a few softer moments.
Grunt is mostly a Blood Knight who is built like a truck, but upon seeing his Parental Substitute Shepard when they reunite in 3, he shoulder-barges past his squad to give Shepard a bear-hug. If you sacrifice the Rachni Queen/Breeder, he will even send you a cheery but poorly spelt drunken email about how he's got his entire elite company of currently-inebriated krogan warriors chanting your name.
Foul-mouthed, unapproachable tough guy Shinjiro Aragaki in Persona 3 turns out to have a well-hidden soft center, hinted at in the main game but put on full display in the female protagonist's route in the portable version of the game.
Eikichi Mischina from Persona 2 is quite the thug, but proximity to Lisa Silverman will reveal his softer side fairly easily, as both know each other's Berserk Buttons and are friendly enough with each other to regularly mash them for light teasing. For all his tough image, he is a strict Bully Hunter and protects students of his school quite ferociously. Even those who have personally moved against him.
Beyond Good & Evil: Mildly demented Double H comes across as strictly military most of the time, always quoting his training manual...right up to the point where he starts repurposing those trite quotes into ways of saying, "Dude, I'm here for you. No matter what."
Kimahri Ronso from Final Fantasy X plays this role; the tallest party member, who is usually cold and aloof - to the point that the main character thought he was mute until he spoke up for the first time. His behaviour concerning Yuna shows his softer centre, which he keeps very well hidden the rest of the time.
Team Fortress 2: In the web made comics there's Saxton Hale's grandfather Barnabus Hale, introduced as randomly fighting a cougar at his employer's, Zepheniah Mann, will reading, wherein he inherits the company. A strip set before shows his employer's wife's death in Childbirth, and while Zepheniah doesn't spare her a thought, Barnabus is in the background crying his eyes out.
The barbarian Bran from A Dance with Rogues is described as being very muscular and strong, and having a bit of a wild appearance, due to his unkempt hair. He's also one of the friendliest companions, who will approve of helping people and, if romanced by the Princess, is shown to be very considerate and gentle.
Persona 4 introduces Kanji Tatsumi, who embodies this trope and takes it to its logical conclusion - his "Bruiser" side was built around his insecurity regarding his soft side, which he was mocked for mercilessly, making him feel like a disappointment to his late father. This contrast, along with his desperate attempts to hide his "girly" traits, has made him sexually insecure and extremely defensive regarding his masculinity, causing him to be further shunned by others. Naturally, he gets better with the help of the protagonist, and the Golden Ending shows him toning down his "tough guy" antics and getting more in touch with himself.
Goliath from Gargoyles is devastated when he believes his Angel of the Night has been murdered by humans. Though his grief runs more to Clifftop Caterwauling than displays of tears.
This also happens in a couple of Looney Tunes in a Chuck Jones series about a huge bulldog named Marc Antony with a tiny, cute, accident-prone kitten named Pussyfoot (a/k/a Cleopatra). That moment when he thinks she's been baked into a batch of cookies...and is then given a kitty-shaped cookie to cheer him up? Not a dry eye in the house.
Buford of Phineas and Ferb. He bursts into tears when his goldfish goes missing. He is thrilled when his bear is restored by the boys' teleportation machine, and when helping Baljeet babysit Perry, speaks to him gently and assures that they will take good care of him.
Rainbow Dash from My Little Pony: Friendship Is Magic. She's brash, arrogant, and can be quite blunt and insensitive at times. She is always willing to solve problems headfirst, but underneath her tough exterior lies a softer, caring side best demonstrated with her friends, her surrogate little sister Scootaloo, and her pet tortoise Tank.
Enzo Matrix from ReBoot becomes this after being trapped in the Games and aging to an adult. He is huge, muscular, tough as nails, with a stubborn streak a mile wide, but the mere thought of losing AndrAIa devastates him. (It's also notable that AndrAIa is the only person in the entire Web who can push Matrix around and get away with it.) He also has a major soft spot where his dog, Frisket, is concerned.
By all accounts, Ernest Hemingway. According to Papa Hemingway, when he was still a struggling writer in Paris, he would sit alone for hours and cry over rejection letters.
Considering the fragile ego of some writers (at the best of times) and the fact the man was seriously depressed, eventually killed himself and could only shut up his inner editor with lots and lots of booze... well that actually isn't that surprising.
MMA fighter Wanderlei Silva is arguably the single most aggressive and intimidating fighter in the history of the sport, bulging with muscles and boasting a disturbing tendency to leave opponents curled up in a puddle of blood and shame after quite literally stomping their faces in. He also adores his fans and has consistently demonstrated himself to be one of the nicest guys in the UFC outside the cage.