Sydney teenager Daniel Christie has died less than two weeks after being punched to the ground on New Year's Eve.
Describing Mr Christie as a "beacon of morality", his family say he died on Saturday morning at Sydney's St Vincent's hospital.
"While no words can describe how crushed we are, Daniel fought courageously over the past 11 days which allowed everyone to say their farewells," his family said in a statement issued by NSW police.
"His death has left us feeling completely destroyed and has torn a hole in the wider community in which he was involved.
"We have been overwhelmed by support and have felt the whole country experience our grief."
The 18-year-old was taken to St Vincent's Hospital in a critical condition after being punched in Kings Cross on New Year's Eve.
Police say they expect further charges to be laid against his alleged attacker, Shaun McNeil, when he next appears in court in March.
McNeil has already been charged with causing grievous bodily harm, assault occasioning actual bodily harm and three counts of common assault.
Police allege McNeil, 25, hit three young men before targeting Mr Christie and his brother, Peter, when the other young men tried to hide behind them.
McNeil, a labourer, allegedly boasted he was a mixed martial arts fighter before punching Mr Christie in the face as he shielded the other men.
Through his lawyer, McNeil has previously told a court that the first group of young men was trying to sell him drugs and he acted to protect his girlfriend who was with him at the time.
He was unable to explain his actions towards the Christies, police facts previously tendered in court said.
A court has previously heard that doctors believed Mr Christie would probably have suffered a serious brain injury if he survived the attack.
People have the right to go out without experiencing violence, the Christie family said.
"No family should be forced to deal with this situation, however we are not the first and we fear that we won't be the last.
"We do not want Daniel's death to be in vain and are committed to rallying for change.
"Daniel lived by the mantra: 'If change can be, it's up to me' - and this is something we will always embrace.
Mr Christie's organs will be donated, the family said.
Since Mr Christie was taken to hospital, there has been increased pressure on the NSW government to tackle alcohol-related violence on the late-night strip and introduce tougher sentencing for perpetrators.
In November, Thomas Kelly's parents Ralph and Kathy started a petition calling for drunkenness to be a mandatory aggravating factor that must be taken into account in sentencing. 18-year-old Thomas Kelly died after being hit with a single punch in Kings Cross in July 2012.
The petition had about 25,000 signatures before New Year's Eve.
But following the alleged assault on Mr Christie, that surged to more than 124,000.
Comment is being sought from acting premier Andrew Stoner.