Friends and colleagues including Warner Bros.
Discovery boss David Zaslav and former A+E Networks CEO Nancy Dubuc paid tribute to Gallagher.
Before launching the Bethesda-based company, he spent over 10 years working at Discovery.
Sean GallagherCourtesy
He started as an AP, then executive producer before becoming head of development for Discovery and TLC.
To work with Sean was always serious fun.
It was the motto of the company we founded together in 2006, Greensfelder said.
Greensfelder met Gallagher on her first day as an intern at Discovery, where he was an AP.
The pair were assigned to edit a show calledPandas: A Giant Stirs.
The culminating scene was when a panda mauled a visiting journalist in the panda reserve in China.
The poor translation from Chinese to English in the doc was He panda cut off his penis.
It was such a pity.
We finished the edit, without that line due to broadcast sensitivities, andA Giant Stirsaired to great ratings.
Zaslav, President and CEO of Warner Bros.
Discovery, said: I was heartbroken to hear of Seans passing.
Our hearts go out to Seans family and loved ones.
He will be missed by many for sure.
Nancy Dubuc, former CEO of A+E Networks and Vice Media, said Gallagher was an amazing person.
Our community that prides itself off on our scrappy nature lost an all time great today.
Well all miss him dearly he was far too young to leave our world.
Not that he ever took credit, she added.
He had a special knack for forging bonds with data pipe collaborators and talent, she said.
But he also suffered no fools.
I didnt swear until I got into business with Sean, but I learned the art from the master.
Sean was not afraid to level an F-bomb upon someone who was a bully or a bad actor.
Ive never worked with someone so honest and brave.
The list of shows Sean has left us is long.
But its his mark of personal integrity that I will hold most dear.
We will miss you dearly, Sean.
He worried about the art, the craft.
He didnt cover his ass, but he covered his producers passion and intelligence.
He fought for you, he fought with you, but he never ever fought against you.
With great love and admiration.
Rest in peace, dear friend.
He said Gallagher was instrumental in Discoverys growth.
He helped build reality television.
If it wasnt for him, reality television wouldnt have the expanse that its had.
He was one of the pioneers, Piligian, who also producedAmerican ChopperandDirty Jobsfor the exec, added.
He was a really good guy, smart and honest.
He was the most honest guy both creatively and personally.
Hes going to be sorely missed.
He called him a close friend and mentor.
He was a creative force who made a huge impact at the peak of the reality genre boom.
He developed a staggering number of iconic reality hits.
As a online grid executive he was fearless.
When he believed in a project he was all in.
Sean was a straight to series guy who followed his gut.
A trait among web connection executives that is now extraordinarily rare.
He built teams with trust as the top priority.
We trusted each other, we cared for each other and we had honest conversations about the creative.
His creativity allowed him to transition seamlessly into a wildly successful producer.
Sean was loved by his friends, family and his colleagues.
He will be missed and remembered often.
Sean was creative, smart and had a true gift for producing.
But my real affection for Sean was who he was a person.
He was a terrific wit, always able to lighten the mood with a funny and well-timed quip.
He will be missed dearly.
The Gallagher Grit was a family hallmark and it bred our awe and respect.
He worked to live, not the other way around, added Greensfelder.
