It was a tragic weekend for family members and friends of 18-year-old actor Robert Knox, who was violently stabbed to death after a brawl outside a London bar on Saturday.

Reports claim that the incident initiated over a stolen cell phone and resulted in Knox’s death as well as four other men stabbed.

According to witnesses, the film star was trying to protect his 17-year-old brother, who was also involved in the brawl, which took place in the south-eastern suburb of Sidcup.

“The life and soul of the party, he was very outgoing, loved sports, and would always strike up a conversation with people,” friends said of the victim.

"He was respectful to others and adored by all his family and friends."

Tom Hopkins, who was also stabbed in the head during the fight, told reporters the following:

“Rob was just trying to help out. He was like that. I grabbed the knife, I didn't know at the time that he had another knife. It was just chaos."

Rob was taken to the hospital where he was pronounced dead.

Knox can be seen playing the role of wizard Marcus Belby in Harry Potter and the Half-Blood Prince, set for release this November.

Our thoughts and prayers are with Knox’s family and friends during this difficult time.

Here's one of many tribute videos for Robert, which can be found on YouTube: