Let's flash back to 2000. In February of that year, Star Trek: Voyager was airing its second-to-last season and was doing everything it could to stay in the zeitgeist. They brought in Jeri Ryan as Seven of Nine in season four, a huge boon for the brand. Later, they started partnering up with UPN who was looking to get as much of their product seen by people as possible.
They landed the WWE (then WWF) in 1999 with the hit Thursday night show, WWF SmackDown. To further capitalize on that, Star Trek began a tradition of bringing over some of the stars of the squared circle. A move that wasn't shocking at all, to be honest, as shows that shared the same network would often bring over other major actors or actresses to co-star. It could and did happen even if the shows didn't share a network.
Like in 1998 when Voyager brought over NewsRadio star and all-around terrible person, Andy Dick.
In 2000, Star Trek reached a deal to bring over the face of the WWE at the time, Dwayne "The Rock" Johnson. Now, everyone knows him pretty much by either moniker, but in 2000, you either knew him as Dwayne Johnson or "The Rock" it seemed.
The Rock was brought in for the 15th episode of season six, Tsunkatse. In the episode, Seven of Nine would get wrapped up in an underground fighting ring where she would end up fighting The Rock. Of course, Johnson wasn't playing his WWE alter-ego, he was playing the Pendari Champion, and that's who's character Ryan's Seven of Nine fought on screen.
Johnson was a good sport and made sure he got along well with everyone on set, Ryan included. He was such a delight that when left, he signed some autographs for everyone. Leaving one for Ryan. However, Ryan had no idea who Johnson was outside of working with him and knew nothing about pro wrestling. So when she saw the autograph, she was entirely confused. In 2020, she told The Big Issue (via SlashFilms)
"It was his first or maybe second acting job ever. I didn't know who he was. I didn't watch wrestling. I wasn't aware of his character of The Rock. [...] So, the first time I met him was a fight rehearsal, and he came in, and he was just a super sweet, unassuming gentle guy named Dwayne. We're talking about our kids and he's just lovely. We had a nice time working together...When I got to my trailer he had left a signed picture in character as The Rock, and it said 'The Rock smells what you're cooking.' Like, what?! It's the weirdest thing I'd ever seen somebody write. Luckily others on set could explain his famous catchphrase. The makeup guys in the prosthetic trailer were like, 'Dude, it's The Rock, that's his thing! He smells what you're cooking!'"
The Rock may not have been a major name outside of the squared circle at the time but as time went on, his reputation and image grew in Hollywood. Now he's one of the most successful actors of all time and is the star of several major film series like Jumanji, and The Fast and Furious franchise (and spinoffs).
He wouldn't be the only wrestler to ever appear on Star Trek, as others like The Big Show (Paul Wight) and Tiny Lister appeared on Enterprise, while infamous 80s wrestler, Tom Magee, appeared on The Next Generation.