Cathey has been nominated for three Emmy awards for his portrayal of Freddie on House of Cards, winning an Emmy for Outstanding Guest Actor in a Drama Series in 2015. The actor has had a decades-long career of notable roles, including in 1994's The Mask, the TV series Oz, and Fantastic Four in 2015
Simon shared a moving remembrance of Cathey, writing, "Reg Cathey, 1958-2018. 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. On wit alone, he could double any man over and leave him thinking. Reg, your memory is a great blessing."
The Wire star Sonja Sohn also tweeted, writing, "1,000,000 times over. Masterful storyteller...an amazing life and human being. Truly a loss for the world."
House of Cards creator Beau Willimon also mourned Cathey's death: "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."
Luke Cage star Mike Colter wrote, "Go gentle into that good night my brother. It was an honor spending time with you on set. Getting to know you as a person and an artist. You will be missed. Condolences to your family. I salute you. #Reg E. Cathey."
Better Call Saul star Michael McKean tweeted, "Reg Cathey was my friend and my wife's friend and a great actor. I am very very sad. RIP, Reg."
Bobby Canavale also expressed his sympathies, tweeting, "We lost a sweet, sweet man and a sweet, sweet, SWEET artist today. Rest In Power, Reg E. Cathey We will miss you."