So there are elements of fascism in both far left and far right ideologies:
Authoritarianism:Absolute, centralized control by a dictator or a single party.
This is present in both the left (eg Venezuela or North Korea) and the right (historically Italy and Chile)
Ultranationalism: Intense devotion to the nation, often involving myths of rebirth following a perceived decline.
Again present in both left and right (China, Cuba, Nazi Germany etc)
Suppression of Opposition: Forcible elimination of political dissent, pluralism, and democratic processes.
Again present in left and right wing politics.
Militarism: Glorification of violence, war, and the military to achieve national goals.
Tends to be associated more with the right wing.
Economic Regimentation:State control over private property and industry, often forcing them to serve the national interest.
Associated more with the left wing.
Anti-Ideologies: Strong opposition and intolerance to opposing views.
Again can be both right wing and left wing.
In summary it is entirely possible for both right wing and left wing extremists to exhibit fascist behaviour. And it's worth noting that both Mussolini and Hitler started out as socialists that then incorporated militarism to morph into fascism.