Detectives are appealing for information after the former Leeds Beckett University student, who had been injured, died in "unexplained" circumstances on Friday.
Police were called around 9.17am that day following a report of a man being found collapsed outside a house on Royal Park Avenue, Hyde Park. He was pronounced dead at the scene.
Mr Loker had been out socialising with friends in Leeds City Centre on Thursday evening and is believed to have gone home in the early hours of Friday.
In a statement, Mr Loker's family said: "Harry was a devoted son, brother and perfect grandson and we could not have asked for more.
"We as a family were extremely proud of Harry and all his achievements and he will be sorely missed.
"This terrible terrible incident has broken us as a family and leaves pain in our hearts."
A post mortem examination has been carried out and has found that Harry had a number of injuries which "cannot presently be accounted for". His death is being treated as unexplained, officers said.
Detective Chief Inspector Jaz Khan of Protective Services Crime said; “We are appealing for information to help us to understand the circumstances leading to Harry’s death.
“At this time, there are a number of injuries that we are unable to account for, and are keeping an open mind as to how these may have been sustained.
“We are treating Harry’s death as unexplained, as we continue to build a picture of his movements after he left the City Centre. I am appealing to anyone who may have seen Harry on Thursday night, or the early hours of Friday morning to come forward as they may hold vital information in helping us understand what has happened.
“Harry’s family are understandably devastated with the news, and officers are continuing to support them at this time. Enquiries are continuing.”
Anyone with any information, or who may have seen Harry is asked to contact Leeds District CID via 101 quoting 13170426310. Information can also be passed anonymously and in confidence to Crimestoppers on 0800 555 111.