You’ve likely seen the video. A dog the size of a small pony, standing on its hind legs, looking more like a grizzly bear than a family pet. People call him a "monster," a "beast," and most famously, the biggest pitbull dog in the world.
His name was Hulk. He weighed a staggering 175 pounds.
To put that into perspective, a standard American Pit Bull Terrier (APBT) usually taps out around 60 pounds. Hulk was nearly three times the size of a normal pitbull. He didn't just break the mold; he shattered the entire scale.
But here’s the thing—if you talk to any serious breed purist, they’ll tell you Hulk wasn't actually a pitbull at all. This is where the story gets messy, fascinating, and a little bit controversial.
The 175-Pound Legend: Who Was Hulk?
Hulk was the crown jewel of Dark Dynasty K9s (DDK9s), a New Hampshire-based kennel owned by Marlon and Lisa Grennan. The facility specializes in breeding and training elite protection dogs for celebrities and high-net-worth individuals.
Hulk became a viral sensation around 2015. One day he’s a puppy, the next he’s a 175-pound behemoth eating four pounds of raw ground beef every single day. He wasn't just big; he was wide. His head was roughly the size of a basketball.
Honestly, it’s hard to wrap your head around his size until you see him next to a human. Marlon Grennan often posted videos of his young son, Jordan, riding Hulk like a horse or napping against the dog's massive chest. It was the ultimate "gentle giant" narrative, and the internet ate it up.
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Is he still around?
I hate to be the bearer of bad news, but Hulk passed away on May 1, 2025.
According to Marlon, he died peacefully in his sleep. For a dog of that size—especially one that likely carried genetics from much heavier breeds—living to nearly 12 years old is actually quite impressive. Most "giant" dogs struggle with joint issues and heart problems much earlier. Hulk's legacy, however, lives on through his offspring, like King Kong, a son who was predicted to eventually rival his father's weight.
The Great "Pitbull" Debate
Is Hulk a pitbull?
Well, yes and no. It depends on who you ask.
If you look at the United Kennel Club (UKC) or American Dog Breeders Association (ADBA) standards, Hulk is a massive outlier. A true American Pit Bull Terrier is an athlete. It’s meant to be lean, agile, and medium-sized.
Hulk was widely considered an XXL American Bully or a "crossbreed." Marlon himself has mentioned in interviews that Hulk’s lineage includes English Bulldog and other "bully" influences. These genes are what give these dogs that massive, blocky bone structure and immense weight.
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Basically, the term "pitbull" has become a catch-all phrase. To the general public, any muscular dog with a square head is a pitbull. To a breeder, Hulk was something entirely different—a specialized "protection" dog bred for maximum intimidation and power.
Why Do These Dogs Get So Big?
It isn't just "good food" or "working out." You don't get a 175-pound dog by accident.
- Selective Breeding: DDK9s specifically selects for size and temperament. They want the biggest dogs that can still move and perform protection work.
- Diet: Hulk’s diet was legendary. We’re talking raw meat, specialized supplements like Bully Max, and enough protein to fuel a bodybuilder.
- Genetics: You can’t train a dog to be that big. It has to be in the DNA. Hulk was a genetic anomaly, a "freak of nature" in the best possible way.
The Controversy Behind the "Monster"
Not everyone is a fan of the biggest pitbull dog in the world.
Veterinarians often argue that breeding dogs to this scale is inherently cruel. Carrying 175 pounds on a frame designed for 60 pounds puts immense pressure on the hips, elbows, and heart. There’s also the "backyard breeder" argument—critics claim that breeding for "size over health" creates a market for unhealthy, unstable dogs.
Then there’s the safety aspect.
Marlon Grennan has always maintained that his dogs are impeccably trained. He trusts them with his children. However, many experts warn that a dog with that much "bite force" and power is a loaded weapon, regardless of how "sweet" they seem. One bad day for a 175-pound dog is a tragedy for everyone involved.
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Hulk’s Legacy in 2026
Even though Hulk is gone, the "XXL Bully" craze is still going strong. You can see his "look" in kennels across the globe. His puppies have sold for tens of thousands of dollars, with some reports claiming a single litter was valued at half a million dollars.
People want the "Hulk look." They want the most intimidating dog on the block that is still a "softie" with the family.
Actionable Advice for Bully Owners
If you're looking to own a dog that aspires to be the next biggest pitbull dog in the world, you need to be realistic:
- Check the Hips: Large bully breeds are prone to hip dysplasia. Never buy from a breeder who doesn't provide OFA (Orthopedic Foundation for Animals) clearances.
- Training is Non-Negotiable: A 100+ pound dog that doesn't listen to "sit" is a liability. You must start professional obedience training at 8 weeks old.
- Watch the Weight: Obesity is the #1 killer of giant dogs. Keep them lean. You should be able to feel their ribs without pressing too hard.
- Socialize Early: These dogs are naturally protective. They need to meet 100 new people and 50 new dogs in their first few months to ensure they stay "gentle giants" and not "dangerous liabilities."
Hulk was a one-in-a-million animal. Whether you viewed him as a biological marvel or a controversial experiment, there is no denying he changed the way the world looks at "pitbulls" forever.
He wasn't just a dog; he was a phenomenon. And while there are other large dogs out there, there will likely never be another Hulk.