Sandra Bullock. Getty Images / Kevin Winter When it comes to movie star salaries, $20 million has become a charmed benchmark akin to the Dow Jones industrial average’s 18,000.

Jim Carrey was the first to receive a $20 million payday for "The Cable Guy," which received mixed notices at the time of its release but has since garnered something of a cult status.

In the 1990s, Mel Gibson, Tom Cruise, and Kevin Costner joined the elite $20 million club.

Today an A-lister is not a guarantee to open a movie and put the proverbial bottoms in the seats, as was demonstrated recently with the Will Smith romantic con man caper, "Focus," which opened big at $19 million; just not Will Smith-big.

A surer thing is a film that is part of a franchise, such as "The Hunger Games," "Twilight," films from the Marvel universe such as "Iron Man" and "The Avengers," and "Fifty Shades of Grey."

But there are still actors whom studio executives deem to be worthy of an at least $20 million payday. According to a recent Hollywood Reporter survey of producers, agents and executives, there are six:

1. Sandra Bullock

2. Leonardo DiCaprio

3. Matt Damon

4. Robert Downey Jr.

5. Angelina Jolie

6. Denzel Washington

It depends, of course, on what type of movie they star in, The Hollywood Reporter notes. Matt Damon will receive that for his movie in the "Bourne" franchise; he did not for George Clooney's more modestly budgeted, "Monuments Men." Likewise for Robert Downey Jr., $20 million is an "Iron Man" payday, not a "The Judge" payday.

There are several other actors whose careers are on a roll and who can command upwards of $15 million for the right film. According to the Hollywood Reporter, they include:

Bradley Cooper. Getty Images / Jason Merritt

1. Ben Affleck

2. Bradley Cooper

3. Dwayne Johnson

4. Jennifer Lawrence

5. Melissa McCarthy

6. Channing Tatum

What does it take to enter Hollywood’s $20 million club? Perhaps a Spectrem Group wealth level study of Ultra High Net Worth individuals with a net worth between $5 million and $24.9 million can offer some insights.

The highest percentage of this wealthy investors credits "hard work" as the primary factor in their financial success. All of the actors in the $20 million club certainly have that in common.

The second most-cited factor is "education." Bullock attended East Carolina University, DiCaprio UCLA, Damon Harvard, and Washington Fordham University. Robert Downey Jr. is the exception; he dropped out of Santa Monica High School to pursue his career.

"Smart investing" is third on the list of wealth creation factors. We might stretch this to mean smart negotiating. Bullock, for example, had an out-of-this-world deal for "Gravity" that wound up earning her more than $70 million.

"Taking risk," another of the wealth creation factors ultra high net worth investors consider most key to their financial success, is emblematic of these elite actors' careers. "Being in the right place at the right time" and "luck" almost certainly could be said to have something to do with their success as well.