I have been watching some older films recently, made somewhere between 10 and 20 years ago. What I noticed was that while many of the male actors were still around and appearing in current films, the female actors seemed to have disappeared, even though they had starring roles in the films I saw.
For example, the 1993 film The Firm starred Tom Cruise and Jeanne Tripplehorn and a host of well known supporting actors. While most of the other male actors like Gene Hackman. Ed Harris, and Hal Holbrook made many films after that and stayed in the public mind, I never heard of Tripplehorn again. Holly Hunter (who has a minor role in the film) had a major role that same year with The Piano but one rarely sees her these days either. The same with Kiss Kiss Bang Bang (2005) that starred Robert Downey Jr., Val Kilmer, and Michelle Monaghan. Monaghan has pretty much disappeared.
I think this goes beyond simple sexism in Hollywood but reflects our society as a whole. When male actors age, there are a huge variety of strong characters they can play, such as corporate executives, senior lawyers, military brass, criminal bosses, grizzled law enforcement officers, spy chiefs, murderous villains, and the like. But these kinds of positions are still largely occupied by men in real life and I suspect that films reflect this fact because screenwriters and filmmakers may not think of casting women for these parts.
For older women, their options are largely limited to playing women in traditionally female roles within the home or in relationship films. The few good roles are few and far between and those seem to be dominated by a few like Helen Mirren, Meryl Streep, Judy Dench, and Maggie Smith. Even a superb actor like Susan Sarandon rarely gets to play any serious role for an older person.
Right now there are actors like Julia Roberts, Nicole Kidman, Jodie Foster, Sandra Bullock, and Halle Berry who are on the cusp of ceasing to be able to play leads and it would be a real shame for them to end up in minor roles or disappear entirely.
One hopes that by the time young actors like Jennifer Lawrence, Natalie Portman, and Scarlett Johansson reach a mature age, things would have changed so that they too don’t end up playing secretaries, doting mothers, and interfering mothers-in-law.