- "Your articles are honest and smart. I could never write the way you write."
"You have two Pulitzers."
- "It's not from the writing. It's from the story. I have craft, you have art."
- —William Dey and Kara Danvers[src]
William "Will" Dey is a renowned reporter, formerly of The Times, Le Monde (The World), and the Daily Mail. He is currently a resident of National City, and a reporter of CatCo Worldwide Media. He was at odds with his co-worker Kara Danvers as he was undercover to learn more about Andrea Rojas and her role in the death of his best friend Russell Rogers.
At various points in time, William started working as a reporter for The Times, Le Monde, and The Mail, all of which he eventually resigned from. At some point, he was renowned for his article on eminent domain in Hartlepool.
In October 2019, William started working at CatCo Worldwide Media. Andrea later introduced William to Pulitzer Prize-winning reporter Kara Danvers, who didn't make a good first impression for him due to her mispronunciation of the town name Hartlepool. Andrea consulted Kara on William rewriting her article on the governor's proposed water tax, an action Kara took offence on as it had all the necessary facts. William explained that the piece was filled with too much unnecessary information and reasoned that every piece has inherent bias, which was the complete opposite of what Kara expected him to say, due to his reputation from when he was still working with The Times of London, when William clarified his works were of their respective natures solely due to the orders of his former superiors. In her suppressed outrage, Kara cleared up what she will and will not tolerate concerning her works, to both Andrea and William's surprise and reaffirmation of her resolution.
At a nightclub, William approached a man and once again demanded that he reconsider working together. The man again declined, before leaving. The next day at work, Andrea Rojas wanted a "sparkly" story of murder. When coming across billionaire, Niles Jarrod who died at a club, she waved it off as nothing important, and William supported her in this. Kara and William found themselves in a verbal altercation. William told the room he had already looked into it, and there is nothing there. Afterwards, Kara confronted William outside about why he was lying. He blew her off, calling her paranoid. Later, William was sitting on a park bench. A man passed him a rolled-up newspaper with money inside of it.
William is working undercover for the London Times and trying to expose Andrea's corrupt schemes.
He was the best friend of Russell Rogers, also known as Rip Roar. Russel was dating Andrea Rojas, and expressed his concerns about her family when they once met at a bar. After becoming Rip Roar and while leaving his house, Russel was confronted by William. William became convinced the Andrea Rojas and Rip Roar were involved in Russell's death, and begun to pursue this to the point of obsession. 
William life appears to remain the same, after the creation of Earth-Prime. He still works as a reporter for CatCo, determined to expose the truth. He is motivated by the fact that his best friend, Russell Rogers, died under suspicious circumstances after turning down a deal from Lex Luthor, leading William to believe Lex is not the good guy he claims. However, in this timeline he joined CatCo to get close to Lena Luthor instead of Andrea Rojas.
William and Kate accompany each other to a toy convention where they run into Lex, much to his own seething anger. After some hostile questioning about possible murder, Lex removes himself for a word with Kara. Back in the office his conversation with Kara about his pending theories on Lex are interrupted when their boss Andrea calls for them. The next day he reveals photos of Lex at Fort Harrison paying off security guards, they decide to work together. After, Kara invites him to her apartment along with the rest of her friends for drinking and games.  Kara later invites him to karaoke night, and after admitting his favorite song to karaoke to is ‘Africa’ Kara’s sister convinced them to sing a duet together. She soon called away by her sister for help with their sick grandmother. Days later she finds him during the temporary blackout at the office, after presenting her with a puzzle for her grandma, and asking her out, Kara politely turns his romantic advances down. He thanked her for her honesty, and promises there are no hard feelings. 
Before work, William brings Kara and Nia coffee. He is assigned to cover his boss's campaign trail for Obsidian Platinum despite her being attacked in the elevator earlier. He agrees, and runs into Supergirl who is Andrea's bodyguard for the day. While talking about his co-worker Kara that he admires, they are interrupted when Andrea is attacked for a second time.  the next day, William meets with Kelly Olsen and discuss Alex and Kara's loss of their father. He confirms Kara has already returned home for the funeral, and Kelly admits Alex is angry and refuses to go. Later William begins to looking into trial users for Obsidian North lenses. The mass majority of whom are simply binge watching their existence. However approximately 50 names are all unresponsive and located at the same address. 
William at first appeared to act highly of himself and look down on others but in reality, this was an act. He started as an arrogant jerk. He sounded like Andrea's lapdog, with his criticizing of Kara's work. It was eventually revealed he is actually a nice guy and he cares about people. The arrogant jerk is just an act. He is working undercover for the London Times and believes that Andrea and her family are criminals. It is the main reason why he workes at CatCo and treated Kara badly because he wants to take down Andrea and her family, and avenge the "death" of his best friend. So, he became Kara's new ally.
- Expert investigator: William has earned a big reputation working with The Times, Le Monde, and The Mail. Being well renowned for his stories. Even being able to track down Kara Danvers while she was Supergirl.
Behind the scenes
- William is the third main character on who doesn't have a comics counterpart, after Alex Danvers and Kelly Olsen.
- However, Nia Nal is an original character while her alter-ego of Dreamer isn't. Nia is based off Nura Nal who in the show is her descendant.
- Staz Nair previously played Dax-Baron, the Kryptonian alter-ego of super-villain Doomsday, in Krypton.