@sunshine62 said:

Robert Redford

1. Robert Redford was in "All the President's Men (1976)" with Stephen Collins.
2. Stephen Collins was in "Star Trek: The Motion Picture (1979)" with Shatner, Nimoy and DeForest Kelley.

James Stewart

Robert Redford also was the main character (with Paul Newman ) in the famous western "Butch Cassidy and the Sundance Kid"

Ted Cassidy (Ruk...in Star Trek episode: "What Are Little Girls Made Of?) also had a role in that same film .

James Stewart.

James Stewart as Wyatt Earp in "Cheyenne Autumn"('64).

Ricardo Montalban ( Space Seed) played in the same film as Little Wolf.

Katherine Hepburn

Katherine Hepburn was in The African Queen with Robert Morley

Robert Morley was in Way, Way Out with Linda Harrison

Linda Harrison was in Airport 75 with Gene Dynarski (Ben Childress - Mudd's Women)

Haley Mills

Haley Mills

1. Miss Mills (Hayley) was featured in "That Darn Cat!" which co-starred Frank Gorshin as a bank robber named Iggy;
2. Gorshin guest-starred on TOS.

Capucine?

Oopppsss! I got carried away and didn't notice Hayley Mills had already been done 😋

What I found.

Hayley's Mills in " The Kingfish Caper ..starring also David Mc.Callum David Mc.Callum starred together with Jill Ireland ( This Side of Paradise .. Leila ) in three films:

1.Robbery Under Arms ('57)

2.Hell Drivers ('57)

3.Jungle Street Girls('60)

David's also starred in "The Greatest Story Ever Told " ('65) .Mark Lenard featured in the same film as Balthazar.

David starred in "Sol Madrid"('68) with Ricardo Montalban.

I also saw that David starred in "King Solomon's Treasure"('79) along with John Colicos.

Capucine

David McCallum was married to Jill Ireland for several years; they divorced about the time she filmed "This Side of Paradise."

Note that Shatner AND Nimoy guest-starred on the same episode of McCallum's series, "The Man from U.N.C.L.E.", "The Project Strigas Affair," directed by Joe Sargent ("The Corbomite Maneuver.") The pilot of "The Man from U.N.C.L.E." was actually called "The Project Vulcan Affair," and guest-starred William Marshall and Roy Jenson.

@jxh13 said:

Capucine?

1. Capucine was in "What's New Pussycat (1965)" with Peter O'Toole.
2. Peter O'Toole was in "Rosebud (1975)" with Kim Cattrall.
3. Kim Cattrall was in _"Star Trek VI: The Undiscovered Country (1991)" with Shatner, Nimoy and DeForest Kelley.

Charlize Theron

Charlize Theron

Theron and Al Pacino.. In "The Devil's Advocate."

Al Pacino and Donald Sutherland ..."Revolution."

Donald Sutherland and Nimoy in ..."Invasion Of the Body Snatchers. ".

PS.....Thanks jxh13..for all the tidbits on Ireland and "The Man From Uncle ".

Vince Edwards

Vince Edwards

1. Vince Edwards co-starred with Stephen Collins in the turgid 70s mini-series, "The Rhinemann Exchange";
2. Collins appeared in "Star Trek: The Slo-Motion Picture" with Messrs. Shatner, Nimoy, and Kelley.

JImmie Walker?

Having a sense of humour makes life easier.😋

In addition .....

Vince Edwards starred with William Shatner in "Sole Survivor" .. Lou Antonio (Let This Be Our Last Battlefield) also featured in the same film.

Jlmmie Walker..

Just checking jxh13....You made a typo .. You meant Jimmie Walker, right?

Jimmie Walker..

"The Greatest Thing That Almost Happened " starring Jimmie Walker and James Earl Jones.

James Earl Jones with Muhammad Ali' starred in "Mohammad Ali'".

Lloyd Haynes (Where No Man Has Gone Before ) featured in the same film.

According to wiki:

Haynes was dropped from Star Trek because series producer Gene Roddenberry preferred actress Nichelle Nichols over him.

Peter O'Toole.

PS:

I haven't got a clue how to link this great actor to TOS yet...😋

He is one of my all time favourites ,though.. I fell for him watching "Lord Jim"..😍

So yes I 'm in the race for this one too ..it will be great to re-visit all his drama packed films .

Peter O'Toole

Yep - thanks. Jimmie Walker of "Good Times" and "Let's Do it Again."

Man, I saw "Sole Survivor," too, back in 1970. Good find. It's a pretty interesting made-for-TV film. Shatner is pretty good.

Lloyd Haynes went on to "Room 222" in 1969, which had one great season and a few good ones.

Peter O'Toole

1. O'Toole played a Roman general in the 70s mini-series "Masada," which also starred David Opatashu;
2. Opatashu guest starred in "A Taste of Armageddon."

Christopher Eccleston?