Everything you need to know about 'Grey's Anatomy' season 18

Scott Speedman will return to "Grey's Anatomy" as a series regular this season, Deadline reported on Thursday.

His character, Dr. Nick Marsh, originally appeared on a single season 14 episode titled "One Day Like This," when he came to Grey Sloan in need of a liver transplant. In that episode, Meredith saves his life and romantic sparks fly between the two, leading Meredith to say he made her feel things she hadn't felt since Derek (Patrick Dempsey) died.

Speedman told Deadline he took the opportunity to return for season 18 because of the "chemistry" he had with Pompeo. While details about his storyline this season are still under wraps, the actor did hint at a "romantic comedy" element that he said reminded him of another one of his hit shows — "Felicity," starring Keri Russell.

Walsh announced via TikTok in early September that she would be donning Addison Montgomery's scrubs again on season 18. 

In an interview ahead of the premiere episode, actor Camilla Luddington told Entertainment Tonight, "She is back and it is kind of like she's never left before. I feel like her presence in scenes is that she kind of owns the hospital." 

Luddington hinted that her character Jo Wilson might get to work with the infamous OB-GYN, Dr. Montgomery: "I think we can say that she is working on a really amazing case that Jo is desperate to get in on. It's always possible there is drama."

Long-time "Grey's Anatomy" guest star Kate Burton will also appear on season 18, Deadline reported in August. Of course, the character of Ellis Grey died on season 3 of the show, but frequently makes cameos from beyond the grave. 

She last appeared in Meredith's dreams on season 15. There is no word on whether Ellis will appear in a dream or via a flashback. But per Deadline, fans can expect to see her in multiple episodes in season 18, beginning with the premiere, which is titled "Here Comes the Sun."

Gallagher, who has recently appeared on other popular shows like "Zoey's Extraordinary Playlist" and "Grace & Frankie" recently told TV Insider that his character Dr. Hamilton has a connection to Meredith's past. 

"In addition to that coincidence, he regards Meredith as a premier surgeon in her field, and so that interests him," the actor said. He also described his character as "really good at his job" and "a pretty good human being." 

Per ABC's description of the episode, Gallagher first appears on the season premiere. He told TV Insider that Dr. Hamilton will be inviting Meredith to the opening of a research library dedicated to her mother, Ellis. 

Abigail Spencer will be reprising her role as Owen Hunt's (Kevin McKidd) sister Dr. Megan Hunt, Deadline reported in early September. 

Per ABC's description of the episode, she'll also begin season 18 on the premiere episode, "Here Comes the Sun." 

ABC's official description of the episode reads: 

"As the city of Seattle revels at the Phoenix Fair celebrating the city's rebirth post-COVID, the Grey Sloan doctors treat a patient who encounters illegal fireworks. Meanwhile, Bailey has her sights set on hiring new doctors, but she's having trouble finding viable options. Owen and Teddy attempt to take the next step in their engagement and Meredith has a surprising opportunity when she meets a dynamic doctor from her mother's past."

In September, Luddington showed off her new blonde locks on Instagram, hinting at a new beginning for Dr. Jo Wilson. She captioned the post "………Season 18" along with the hashtags "#JoWilson #blonde #NewEra." 

Maybe Jo Wilson needs some spice in her life because she's losing sleep as a new mom to baby Luna. "She is dealing with a single-working mom and not having much help," Luddington told Entertainment Tonight. Jo is also an intern again because she's transferring her specialty to OB-GYN. 

This all fits with the "Grey's Anatomy" season 18 tagline, "A new tomorrow. Today."

This season, Meredith Grey is done having dreams about reuniting with dead loved ones (and former fan-favorite actors like Eric Dane, Patrick Dempsey, Chyler Leigh, and TR Knight) on the beach while sick with COVID. So, the fictional world of "Grey's Anatomy" is likely to move on from the pandemic, even if the real world hasn't.

"This season is actually what we thought last season would have been," Chandra Wilson told GMA. "This season we start our world with the belief that everyone did what they were supposed to do and they got vaccinated and we got COVID under control and now we can take care of all the other things that happen in life that bring people into the hospital."

Meredith Grey's mother Ellis Grey opens the season 18 trailer asking her daughter, "You've survived the unthinkable. What are you gonna do Meredith?" 

We can't exactly answer that question, but we know what her friends might do. Teddy and Owen appear to be having an impromptu wedding, Amelia (Caterina Scorsone) and Link (Chris Carmak) have a lot to work through after she turned down his epic proposal on the beach last season, and the paramedics on "Station 19" have lost their rig.