Police are urgently appealing for information to find the 42-year-old, who may be in the Blackpool area.
William was last seen at around 11am on Wednesday (April 18) at an address on Hargrave Drive in Ellesmere Port.
He is described as white, around 6ft 2 in height, of a stocky build with a mousy brown hair and a short cut beard.
William is believed to have been last seen wearing a bright orange coat with either jeans or joggers with trainers.
Inspector Mike Skillen from Cheshire Police said: “Extensive enquiries to locate William are currently ongoing and we are increasingly concerned for his wellbeing.
“William resides in the Great Sutton area but he is also known to have links to the Blackpool area and we believe he may have travelled there.
"I would urge anyone who has seen or spoken to him since he disappeared to contact police on 101.”
If anyone has seen him or has any information on his whereabouts, they're urged to contact police on 101 quoting incident number 39509 or the charity @MissingPeople on 116 000.