LONDON — Paramount+ flexed the star power of its shows as it prepares to launch in the United Kingdom with an event attended by Sylvester Stallone, Viola Davis, Kevin Costner, Jessica Chastain and more.

The expansion delivers overseas some popular programs like Costner’s “Yellowstone” and “Star Trek Discovery” to U.K. audiences. Subscribers will also get to see Stallone’s scripted television debut in “Tulsa King,” in which he plays a Mafia capo.

“It’s just something I’ve always wanted to do, and I don’t know how I’ve avoided playing a mobster my whole life. I don’t get it — that’s the way people look at me anyway. So finally, an opportunity comes along,” Stallone said.

The service launches Wednesday.

Paramount+ joins an already crowded market of streaming giants in the U.K. and will compete with Amazon, Netflix and others. It arrives with more than 8,000 hours of programs, including the expanding “Yellowstone” series. Paramount and MTV Entertainment Studios announced Monday that its next spinoff starring Helen Mirren and Harrison Ford would be titled “1923” and would focus on the Prohibition era following World War I.

Chastain stars with Michael Shannon in the series “George & Tammy,” while Davis, Michelle Pfeiffer and Gillian Anderson appear in “The First Lady,” about U.S. presidents’ wives.

Sonequa Martin-Green was thrilled that her series “Star Trek Discovery” will reach a wider audience. “Especially with ‘Trek,’ I think it should always be globally celebrated because of what it represents and because of what it’s done.”

Miranda Cosgrove’s hit series “iCarly” will also feature on the streaming platform.

“Hopefully it’ll make people happy here like it did in the United States,” said the 29-year-old actor, singer and producer. “I’ve played the character Carly for most of my life. So, yeah, it’s definitely something that I hold very dear to my heart.”