Rob Knox (right) had a small part in the new Harry Potter film
A man accused of stabbing an actor to death in a fight said he "had no other option" but to defend himself, the Old Bailey heard.
Rob Knox was knifed during the fight outside the Metro Bar in Sidcup, south-east London, in May last year.
Karl Bishop, 21, accused of Mr Knox's murder, alleges he was defending himself from an attack by a group.
Mr Bishop, from Carlton Road, Sidcup, denies murder and five charges of wounding with intent to cause GBH.
"From what I can remember I was always going backwards and just swinging and trying to keep people away from me but they just kept coming towards me," he said.
"You wouldn't think people would run at someone who's got a knife. I didn't intend to wound anyone at all, but they attacked me.
"There was no other option. They ran at me, they attacked me. They had me surrounded at one point so I couldn't go anywhere even if I wanted to."
He said that a week before Rob was killed, he had been punched to the floor and stamped on during a fight outside the Metro bar with a group of youths, before running off but being caught and being beaten up again.
On the night of the stabbing Mr Bishop said he was persuaded by his friends to go to the Metro bar.
He said he was attacked again when he got there and so went home to get two knives out of his kitchen drawer.
"I took two because two is scarier than one and I was angry at the time. I'd just been beaten up again - twice in two weeks," he said.
"My assumption was that it was the same people as it was the same place, so I was quite angry."
The trial continues.