You can thank Smallville for the CW. The creation of the CW was aided by the success of a number of television shows on the WB after the latter network's merger with UPN. At the time that this happened, Smallville was in its fifth season and was hugely popular, giving The CW a major leg-up on the competition. The DC superhero show that unquestionably influenced the network to make shows like Arrow, Legends of Tomorrow, Supergirl, The Flash, and Black Lightning. Without a doubt, the success of the Superman origin show was a result of the brilliance of the cast. Tom Welling was the most perfect man to play Clark Kent, even though the role almost went to a Supernatural actor. That's just one of the many behind-the-scenes details of the making of Smallville.

But it wasn't just Tom Welling that brought this show to life, it was also the incredible cast of supporting characters. Here's how the masterminds behind Smallville found these iconic actors...

Casting The Man Who Didn't Really Want To Play Superman

It was Kristin Kreuk (Lana Lang) who was cast first in the Superman origin series, according to an exclusive interview by TV Line. In fact, actors like Michael Rosenbaum (Lex Luther) and the now-disgraced Allison Mack (Chloe) were brought on before director David Nutter and the creators of Smallville, Alfred Gough, and Miles Millar, could sign Tom Welling (who seemingly vanished after Smallville). It took the show reevaluating how much Superman was actually going to be in the show that convinced Tom. According to the interview, he was far more interested in Clark Kent before he became the most iconic superhero ever created.

"I knew Tom was the perfect guy when Clark runs into Lana Lang for the first time," The director of the pilot, David Nutter, said. "Lana had a kryptonite necklace on her neck, so Clark tumbled onto the ground, dropping his books. I said to myself, 'That’s him.'"

Related: Who Is 'Superman' Tom Welling's Ex-Wife, Jamie White-Welling?

Tom also tested really well with Kristin. Their chemistry was off-the-charts and the producers knew that they had something special. On top of this, Tom was someone they all wanted to work with for a personal reason...

"Tom is very down-to-earth and straightforward, and a lot of that honesty you see in Clark is Tom," executive producer Kelly Souders explained. "Tom was not somebody who got into this because he wanted to be famous, and that really adds to him being Clark Kent. There are obviously some real differences between them, but there are definitely similarities."

Casting The Heroes And Villians Of The Town Of Smallville And City Of Metropolis

Kristin Kreuk was right out of high school when she was asked to audition for Smallville, which was cast and shot in Vancouver, British Columbia, Canada. She had little to no experience in the business, but she blew everybody away when she auditioned for the role. The same was true for Allison Mack, despite being the only white actor auditioning for a character that was designed to be 'African-American or Latina'. But finding the right Lex Luthor was a little more challenging...

Related: The Truth About Casting Jesse Eisenberg As Lex Luthor

"I was doing a lot of comedies at the time, so when my agent approached me about Lex, I wasn’t really interested," Michael Rosenbaum told TV Line. "It was The WB and I thought it would be a teen soap opera; I had no idea the kind of money they were going to put behind it and how smart the concept would be. Supposedly they went through hundreds of actors and still couldn’t find their guy so they asked me again to read. They said they wanted someone who had comedic timing, charisma, and a sense of danger, and I think I still have the [audition] pages where I marked, 'Be charming here,' 'Be funny here' and 'Ooh, be dangerous here.'"

"When it comes to playing Lex Luthor, there was something sympathetic about Michael Rosenbaum’s version. He brought humanity to it," Kelly said.

Related: Here's What Michael Rosenbaum Has Been Up To Since 'Smallville'

Rounding out the cast was a list of more established stars playing the main characters' parents. Of course, this includes John Schneider (Jonathan Kent) and Annette O'Toole (Martha Kent), both of whom were hugely impactful to Tom Welling's life, according to him. The same could be said for John Glover to Michael Rosenbaum, who played Lionel Luthor.

The casting of these three more established players allowed for a more flexible casting process for the younger stars. These actors didn't need to be experienced. They just needed to be engaging, attractive, and able to bring these iconic characters to life.

Next: 'Batman v Superman' Writer Chris Terrio Says 'Justice League' Flopped Because Executives Didn't Trust Writers