His death was announced Friday night by David Simon, the creator of "The Wire," who paid tribute to the late 59-year-old actor on Twitter.
"Not only a fine, masterful actor -- but simply one of the most delightful human beings with whom I ever shared some long days on set," Simon wrote. "On wit alone, he could double any man over and leave him thinking. Reg, your memory is a great blessing."
More details of Cathey's passing, including the circumstances surrounding his death, were not immediately available.
The Huntsville, Alabama, native was born into a military family in August of 1958. He took an interest in theater at the age of 9 after attending a United Service Organization show in West Germany, where he was raised.
He attended the University of Michigan and the Yale School of Drama.
Over more than three decades, Cathey was praised for his commanding baritone voice and the unexpected sense of humor he brought to his roles.
He also appeared in two HBO series -- "The Wire" as Normal Wilson, a Baltimore political operative and in "Oz," where he starred as warden Martin Querns.
He also had roles in several network TV series such as "Law & Order," "30 Rock," "Grimm," and in movies like "Fantastic Four" and "Hands of Stone."
In 2015, he won an Emmy for his role in "House of Cards" as Freddy Hayes, the owner of a barbecue restaurant that Kevin Spacey's character Frank Underwood often visited.
Netflix issued a statement Friday saying employees were heartbroken by Cathey's passing.
"Reg was the kindest man, the most giving actor, a true gentlemen. Our sympathy goes to his family," the statement said.
"House of Cards" creator Beau Willimon tweeted about Cathey's passing, "Reg Cathey was one of a kind. Brimming with life force, generosity, humor, gravitas and a fountain of talent. Loved by everyone lucky enough know him and work with him. He will be greatly missed. Rest In Peace, Reg."