Which films where the main lead plays an assassin are really good?

I always liked the Mechanic with Charles Bronson.

^^Yes that was good. Like the opening scenes.

Really good, in various ways:
The Day of the Jackal (1973)
Léon: The Professional (1994)
In Bruges (2008)
Le Samouraï (1967)
Pulp Fiction (1994)
Kill Bill Volume I (2003)

Good… in a way…
Prizzi’s Honor (1985)
The American (2010)
Hanna (2011)
John Wick series…
The Bourne Identity (2002)

@Zaku Thanks so much. I’m going to check out Le Samourai and Prizzi’s Honor which I’ve heard of but never seen yet.

I also recall a pretty interesting assassin ( not a lead ) played by Steve Buscemi.

Bestseller with Dennehy and Woods which is now in Amazon Prime is a film I revisit once every several years.

Le Samouraï is a classic landmark film, though is a slowish-paced old French film. If you do like it, Le Cercle Rouge (1970) might interest you, though it’s about a thief, or Revolver (1973), though it’s an Italian film about an officer going after his wife’s mob kidnappers.