Mandla Hlatshwayo and his friend were shot after confronting a group of men who had robbed women of their mobile phones in a pub in Soweto.
Those who knew the 40-year-old have described him as a selfless man.
South Africa has one of the highest murder rates in the world with more than 50,000 cases reported every year.
Many are using social media to send messages of condolences to the family of Mr Hlatshwayo, who was also a disc jockey for local radio station Jozi FM.
The hashtag #RIPMandla has been trending since news of his death broke on Monday morning.
Jozi FM head Mpho Mhlongo, who confirmed the star's death, noted that Mr Hlatshwayo's father was also killed some years ago during a robbery.
Mr Hlatshwayo's death has sparked a debate around how to tackle the country's rampant crime levels but it makes many realise there are no easy solutions, says the BBC's Pumza Fihlani in Johannesburg.
There have been no arrests yet.