Many of York's co-stars took to Twitter to pay tribute to the actor.

Actor Mark York, who played Billy Merchant in the US edition of The Office has passed away at the age of 55. According to his family, he died following a "brief and unexpected illness". The Montgomery County coroner's office confirmed his death yesterday. An obituary from his family that appeared in Radio Times read: "Even though he had been paraplegic since 1998, he had such an outgoing, uplifting, positive attitude and personality." Mark York played Billy in four episodes of The Office between 2006 and 2009. His character, who is also paraplegic, leads a meeting on disability awareness that doesn't go as well as he had planned. Fans praised York's performance, and said that he received letters who appreciated the way his character "shed light on how crazy office politics can be." "The letters I get about the character are great," he told People Magazine in 2010. York also had parts on CSI: New York and 8 Simple Rules. https://twitter.com/jennafischer/status/1397068031751200775?ref_src=twsrc%5Etfw%7Ctwcamp%5Etweetembed%7Ctwterm%5E1397068031751200775%7Ctwgr%5E%7Ctwcon%5Es1_&ref_url=https%3A%2F%2Fwww.rte.ie%2Fentertainment%2F2021%2F0525%2F1223796-the-office-us-actor-mark-york-dies-aged-55%2F As well as his acting career, York was involved in advocacy for disabled actors, and supported research efforts for spinal cord injuries. Additionally, he served as the Southern California representative for SCI Research Advancement, a non-profit research organisation. A number of The Office stars took to Twitter to pay their tributes to the actor. Jenna Fischer, who played Pam Beesly, said on Twitter: "Mark was a lovely man and a pleasure to work with. Very funny every time. Much love to his family." Rainn Wilson, who played Dwight Schrute said: "He was a terrific human, a positive force and a dynamic actor. You will be missed." Angela Kinsey, who played Angela Martin tweeted: "Very sad to hear about Mark's passing. He was so talented and kind and will be missed. My thoughts are with his family. May he rest in peace."