Molotov cocktails and tear gas engulfed the streets of Athens as a left-wing rally to mark four years since the murder of an anti-fascist rapper turned violent.
The demonstrators also paid tribute to anti-fascist activist Heather Heyer, who was killed in a vehicle ramming attack in Charlottesville, Virginia in August.
After gathering in the city’s Syntagma Square, the demonstrators marched to the US Embassy, before trying to make their way to offices of Golden Dawn, chanting: “Pavlos is alive! Crush the Nazis!”
The protesters demanded Golden Dawn’s offices be shut down and its members jailed.
But their path to the offices was blocked by riot police and dozens of hooded demonstrators broke off from a march, Reuters reported.
Some threw Molotov cocktails and the police responded with tear gas.
The marchers mostly dispersed, but a small group threw more fire bombs outside police headquarters. Three have been detained.
The murder of Fyssas, who used the stage name Killah P, caused shockwaves among Greek’s left wing community and sparked weeks of protests and disorder.
World news in pictures
Giorgos Roupakias, an admitted Golden Dawn supporter, admitted stabbing Fyssas to death but the case is yet to go to trial.
Golden Dawn’s leader, Nikolaos Michaloliakos, has accepted his party holds “political responsibility” for the killing but is not criminally liable.
But many people believe the murder was carried out with the knowledge of senior party officials.