A few more lesser known supporting actors worth checking out for their work if anyone wants to do more mini marathons...
ELIAS KOTEAS
The Prophecy, Fallen, Shooter, Sugartime, The Thin Red Line, Teenage Mutant Ninja Turtles, Shutter Island, The Curious Case of Benjamin Button, Apt Pupil, Zodiac, Collateral Damage, Some Kind of Wonderful, Tucker: The Man and His Dream
ANTONIO FARGAS
Shaft, Whore, Across 110th Street, Pretty Baby, Busting, Foxy Brown, Cleopatra Jones, The Gambler, Car Wash, Next Stop Greenwich Village, Shakedown, I'm Gonna Git You Sucka, Firestarter.
PAUL McCRANE
Fame, Robocop, Rocky 2, The Blob, Purple Hearts, Strapped ... then became more of a TV guy.
RICHARD LYNCH
An interesting story...high on acid one day he set himself on fire and burned his face off. Still had a good acting career after that.
Scarecrow, Open Season, Halloween (2007), Alcatraz: the Whole Shocking Story (TV movie) ... but he did mostly terrible straight to video movies or else TV. He guested on a lot of classic shows and if you can find his episodes it could be a starting point to seeing if you want to check out more of the show, aside from seeing him in action.
- Streets of San Francisco, Hunter, Baretta, Battlestar Galactica, Serpico, Buck Rogers, Charlie's Angels, Airwolf, Star Trek: TNG, Six Feet Under. Somehow he never did Miami Vice.
MICHAEL WINCOTT
Robin Hood: Prince of Thieves, The Count of Monte Cristo, The Assassination of Richard Nixon, The Crow, Alien: Resurrection, Basquiat, Talk Radio, 1492, The Doors, Romeo is Bleeding, The Three Musketeers, Dead Man, Strange Days, Along Came a Spider, The Diving Bell and the Butterfly.
CLIFF CURTIS
Training Day, Whale Rider, Collateral Damage, Doctor Sleep, Sunshine, The Piano, Bringing Out the Dead, Fracture, The Fountain.
GARRETT DILLAHUNT
No Country for Old Men, Last House on the Left, Looper, 12 Years a Slave, The Road.
CLANCY BROWN
Highlander, Bad Boys, The Hurricane, The Shawshank Redemption, Starship Troopers, The Bride, Shoot to Kill, Blue Steel, Last Light.
MICHAEL IRONSIDE
Scanners, Nuremberg, Total Recall, X-Men First Class, The Machinist, Turbo Kid, Starship Troopers, Top Gun.
JAMES TOLKAN
Top Gun, Serpico, Back to the Future 1-3, Bone Tomahawk (playing piano for a minute at the start), WarGames, Opportunity Knocks, The Amityville Horror, Wolfen, Author Author, Armed and Dangerous.
BRIAN THOMPSON
Cobra, Lionheart, The Terminator, Alien Nation, Miracle Mile, Dragonheart, and a noteworthy episode of Star Trek TNG.
RON SILVER
Timecop, Blue Steel, Mr. Saturday Night, The Arrival, Reversal of Fortune, Semi-Tough, Romancing the Stone, Married to it.
ROBERT PROSKY
Thief, Hoffa, Mrs. Doubtfire, Last Action Hero, The Natural, The Lords of Discipline, The Keep, Broadcast News, Outrageous Fortune, Big Shots, The Great Outdoors, Things Change, Gremlins 2, Far and Away, Green Card, Rudy, Miracle on 34th Street, The Chamber, Dead Man Walking, Mad City, The Scarlet Letter, Eye See You / D-Tox, Death to Smoochy.
JT WALSH
Good Morning Vietnam, Breakdown, A Few Good Men, Sling Blade, Hannah and Her Sisters, Tequila Sunrise, The Grifters, Misery, Outbreak, Narrow Margin, Backdraft, The Russia House, Hoffa, Sniper, Loaded Weapon 1, Needful Things, Red Rock West, The Client, The Last Seduction, Silent Fall, Nixon, Miracle on 34th Street, The Negotiator, Executive Decision, Pleasantville.
Those are the character actors where I thought it might be fun to watch the movies and take note of their appearances and performances. All of those should be at least worth a watch.
Who else might be fun to look up and/or watch for... ABE VIGODA (Look Who's Talking, The Godfather), HART BOCHNER (Die Hard, Mr. Destiny), ANDREW ROBINSON (Dirty Harry, Hellraiser), MIGUEL FERRER (Robocop, Traffic), IAN BANNEN (The Offence, Braveheart), HENRY SILVA (The Manchurian Candidate, Ghost Dog: Way of the Samurai). Some damn fine actors. Andrew Robinson came up with the line "Jesus wept" on set to close out his character's story in Hellraiser.
In the OP I highlighted in yellow the list of leading actors who could give you a great marathon if you took their movies from the 1970s and 1980s.
Some of the following are obvious choices, but these are more leading actors in general whose filmographies would be worth a watch...at least the stuff that went to theaters or in the general years indicated...
Marlon Brando - no kidding really, but if you go beyond his legendary stuff you'll get some interesting movies like The Missouri Breaks with Jack Nicholson, Last Tango in Paris, The Island of Dr. Moreau, etc. He never descended into straight to video junk territory which is a blessing.
Michael Douglas - kind of a similar comment. Go through it all and you'll get some lesser known decent or at least watchable stuff at the beginning (Running, Coma) and the later years (King of California, Wonder Boys, Behind the Candelabra). There will be some junk to wade through in the post-Traffic years.
Kirk Douglas - hey, if you're doing Michael. You'll come across some forgotten decent stuff like Tough Guys and Amos.
James Dean - there aren't that many movies so it's pretty easy to cover them.
James Stewart - one of the best and most natural actors from the pre-Brando era.
Tom Cruise -
@revoltub has this covered.
Clint Eastwood -
@The Good The Bad The HBK has this covered.
Lee Van Cleef -
@The Good The Bad The HBK has this covered.
James Coburn - they won't all be winners but there's plenty of good stuff. He was doing strong supporting work at the end like Affliction and Young Guns 2.
Arnold Schwarzenegger - 1976 to 2002 and then selected films.
Sylvester Stallone - 1973 to 2000 and then selected films.
Jean Claude Van Damme - 1985 to 1998 and then selected films.
Harrison Ford - 1973 to 2002 and then selected films.
Bruce Willis - Moonlighting and 1987 to 2007. You can stop a little before 2007 if so inclined.
Peter O'Toole - if you go to the end you'll get his last Oscar nomination for Venus and also some pretty awful, maybe so bad it's good stuff like Supergirl.
Gene Hackman - he got out of the game before he had to start making crap in any measurable quantity.
Sam Rockwell - a fantastic actor right from day one.
Viggo Mortensen - the same, you can see he has chops just from watching him listen at the table with the main characters with no lines in Witness. Then he started killing it with smaller roles in Young Guns 2 and The Prophecy. It was just a matter of time before he became an A-list leading man.
Sean Penn
Sidney Poitier - I mean he did end up doing stuff like To Sir With Love 2 as a TV movie...but nobody stays at the top forever. Except Tom Cruise apparently.
Leonardo DiCaprio - honestly en route to a Tom Cruise style run at the peak of the mountain...we'll see how long he holds up.
Denzel Washington - he's been doing it longer than Leo and damn near as long as Mr. Cruise.
Tom Hanks - see what I just said about Denzel. A Tom Hanks movie is less of an event now than a Denzel film, but he is still making stuff that is at least worth putting on film and watching. Obviously it takes no significant knowledge to recommend Tom Hanks films.
Matt Damon - hasn't had to do junk to pay the bills yet.
Steve McQueen - not too original a recommendation but he died before he could get old enough to think about having to make junk movies to pay the bills.
Rock Hudson - he was doing TV movies like World War 3 at the end but that was still worth a watch. Obviously he's a part of history not just for acting but for how he passed away.
Charlton Heston - I figure people might not see stuff like Soylent Green or The Omega Man or Planet of the Apes 2 otherwise. And of course there's his appearance in Fahrenheit 911 which I am guessing he would prefer to not have on his resume.
Peter Sellers
Henry Fonda
Robin Williams
Richard Gere
Edward Norton
Val Kilmer - he has done some interesting low key stuff like Felon, got started with a decent TV movie The Man Who Broke 1000 Chains. Did other at least okay mostly forgotten or overlooked stuff like At First Sight, The Island of Dr. Moreau and Real Genius.
Kevin Costner - he's a heck of a director too.
Michael Keaton - start to finish for the most part. Maybe descended into a bit more crap for money than Tom Hanks at some points but he is also doing better stuff than Hanks as of late like Spotlight and Birdman and The Founder. They had a similar trajectory you will see from comedy (Keaton started as a standup comedian) to serious drama. Keaton did probably make this transition a bit earlier with stuff like Clean and Sober.
Tupac Shakur - hey why not. He was a pretty decent actor, didn't make that many movies before he passed away, and none of them totally sucked.
Charlie Sheen and Emilio Estevez - they might be a little hard to take seriously now, especially Charlie, but their stuff from their first movie through to about 1996 is solid.
SOME ACTRESSES WHERE THEIR ENTIRE FILMOGRAPHY OR CLOSE TO IT IS WORTH A GOOD LOOK... (in addition to those highlighted in yellow in the OP)
Jodie Foster
Elizabeth Taylor
Audrey Hepburn
Katherine Hepburn
Meryl Streep
Julia Roberts - once she got the baton with Pretty Woman she held onto it and ran for a long time.
Frances McDormand
Sissy Spacek - may trail off in quality somewhere in the 90s.
Jessica Lange - may trail off in quality somewhere in the 90s.
Sigourney Weaver - Everything from the very start to maybe Alien Resurrection or Galaxy Quest and then a film here or there like Avatar.