As a Charlize Theron fan, I'd like to have seen:
"2 Days in the Valley" - Theron v Teri Hatcher.
Theron goes for a gun in her handbag; they fall to the floor and Charlize is shot as they wrestle for it. Hatcher runs away, Charlize dies!
(I'd much prefer that the writer allow Theron - the much bigger, stronger, younger, actress - to win the fight by having Teri go for the gun and Charlize kick Hatcher's "desperate" butt around the room. (This was voted "best movie catfight" by at least one 'expert')
"Aeon Flux" - Theron v Caroline Chikezie.
Theron and Caroline in a knockdown brawl. Again, it ended with CT escaping (by the skin of her teeth) instead of doing what any heroine worth her salt would do - win the fight by kicking butt!
"Head In The Clouds" - Theron & Penelope Cruz.
No fight in this one, but several opportunities for a sexfight or at the least, wrestling in bed. (shame on the writers!)
"Devil's Advocate" - Theron & Connie Nielsen. Theron & Tamara Tunie. Theron &

.
Plenty of opportunities (and conflict) in this tale that could have led to a confrontation. In the dressing room scene, Tunie appears to be "coming on" to Theron (having her feel her breast) for one. Charlize played the "fish out of water" in this film, with her seeming to be a step out of phase with the lusty women of the New York legal wives club. Wanted her to slap the saliva outta somebody!!
There have been others, but basically I blame the scriptwriters and directors for missing far too many chances to let highly competitive and successful actresses "unleash their inner beast" on celluloid....or on digits these days!
Of course, fans of almost ANY actress could post a similar (even longer) list of "missed opportunities" - you could start in the early 20th century with silent films. How many scenes could have used an actress winding up followed by a "POW" sign. (who needs dialogue?)