Chris Hardman, who starred in the British reality program "Rock School," has died aged 24.
The singer and actor, who went by the name Lil' Chris, became famous after joining Kiss frontman Gene Simmons' British Channel 4 show in 2006.
He went on to have a top five hit with his first single "Checkin' It Out" shortly after.
In 2012 he starred in the musical "Loserville: The Musical" at the West Yorkshire Playhouse in Leeds.
Allan Dodgeon, who managed Hardman for a year from 2013 at AD Records, told Sky News: "He was a talented young artist who we had the pleasure to live and work with for over a year. We are completely shocked and saddened and our thoughts are with his family."
Lil' Chris sent his last tweet six days ago when he wrote: "Good morning everybody! Lovely day! Love you all x"
It is believed he had suffered from depression. A Suffolk Police spokeswoman said: "Police investigating the sudden death of a man in Lowestoft can confirm they are not treating it as suspicious.
"Officers received a call from the ambulance service on Monday 23 March at around 11.45am and attended an address in Union Road following a sudden death of a 24-year-old man.
"A post mortem examination is due to take place to establish the cause of death and a file will be passed to the coroner in due course and an inquest opened."
British boxer Anthony Ogogo was one of the first to pay tribute to the singer on Twitter: "Who remembers Lil Chris from Rock School? He went to the same school as me, super talented kid has died.
"Thoughts go out to his family. Such a shame. Really nice guy and positive role model for our area #ChChChCheckingItOut."
Caroline Flack, who met the star on children's show "TMI," said: "Oh my god. Lil Chris. He was a regular guest on 'TMI.' Always always such a polite lovely guy. That's so sad."
Oh my god . Lil Chris . He was a regular guest on TMI. Always always such a polite lovely guy . That's so sad ��— caroline flack (@carolineflack1) March 24, 2015