Favorite or memorable on-screen Duels

1 on 1, 2 on 1, or 2 on 2...
Whether it was with guns, swords, hand-to-hand, etc...
What characters/actors were involved and what movie was it in?

I have 2:
1. Obi-wan Kenobi vs Darth Maul (Star Wars ep 1)
2. Zhang Ziyi vs. Michelle Yeoh (Crouching Tiger Hidden Dragon)

 

The obvious, Duel, starring Dennis Weaver and the unknown truck driver. A classic by Steven Spielberg, his first.

 

damn you Death you beat me to it...

Duel! the best chase movie.. how far can a DODGE DART get on a gallon of gas?
or was it a Plymouth?

 

ROCKY BALBOA vs. IVAN DRAGO!

 

John vs. Keith

 

The Man With No Name vs. Angel Eyes vs. Tuco (The Good versus The Bad versus The Ugly)

 

The Dude Vs. German Nihilist

 

cant believe you left out this duel out.....

 

Classic conflict:
James Bond (Sean Connery) VS. The Man from SPECTRE (Robert Shaw),
on the train in From Russia With Love