Barkan, who was diagnosed with ALS in 2016, was 39 years old.
His wife, Rachael, announced his death online on Ady's X account.
"I'm devastated to share the news that Ady has died from complications of ALS," Rachael Barkan wrote. "You probably knew Ady as a healthcare activist. But more importantly he was a wonderful dad and my life partner for 18 years."
Barkan, who lived in Southern California, is survived by his wife and their two children.
Our America: Accomplices - The Story of Ady Barkan | Full Episode
Our America: Accomplices - The Story of Ady Barkan | Full Episode
Barkan co-founded the nonprofit Be A Hero which works to expand access to healthcare services.
Be A Hero's co-executive director Jamila Headley wrote:
"Ady was a brilliant strategist, an incisive communicator, and powerful advocate who, while fighting for his own access to health care following his ALS diagnosis in 2016, became a leader in the effort to save the Affordable Care Act so that tens of millions of people in this country could also get the health care they deserve."
Barkan, who attended Columbia as an undergrad and then Yale for his law degree, was active in political causes since his college years, but became publicly known for his healthcare advocacy after his ALS diagnosis. During an exchange with Arizona Sen. Jeff Flake that was caught on camera Barkan urged the senator to "be an American hero" in voting for health-care access - inspiring his Be A Hero effort.
He continued with appearances before Congress and national efforts to protect and expand healthcare access.
In 2018, he sued the Southern California-based insurer Health Net for allegedly denying benefits to members.
A father fights terminal illness and healthcare provider
A memoir titled "Eyes to the Wind: A Memoir of Love and Death, Hope and Resistance" was published in 2019.
By 2020 he was named on Time magazine's list of the Most Influential People.
"After his diagnosis, Ady chose to use the time he had left fighting to create a country where health care is treated as a human right," Be a Hero wrote in a tribute to the organization's founder.