The Boys star Karl Urban teases Jeffrey Dean Morgan's mystery character with season 4 photo

Filming has officially wrapped on The Boys season 4, and star Karl Urban is commemorating the moment with a photo of him and guest star Jeffrey Dean Morgan.

The Walking Dead veteran, who's been fighting tooth and nail to land a spot on the series, is seen in a black suit and blue tie next to Urban's Billy Butcher. Morgan's role is still a mystery.

"Oi!" Urban began an Instagram post, using Billy's familiar exclamation. "That's a picture wrap on season 4 [of The Boys]. Massive thank-you to our phenomenal crew & cast. Love you guys! I'm not allowed to post any photos from set…soooo here's a snap of [Jeffrey Dean Morgan] & moi on the set of a Cadillac commercial…"

The caption was followed by a smirking emoji face to suggest sarcasm and an update that season 4 is "coming soon…ish" to Amazon's Prime Video.

In January 2020, showrunner Eric Kripke, who worked with Morgan on Supernatural, had a Twitter exchange with the actor, who said he would join season 3 "in a heartbeat." However, scheduling wouldn't allow it at the time, and that continued to be a problem.

Catching up with Kripke around the time of season 3, the producer told EW, "We might still remain star-crossed, unfortunately, because I did ask. We had a role come up [in season 4], and my first question was, 'Well, is Jeffrey available?'"

And then it happened: Amazon officially announced Morgan for a mystery guest-star role in season 4 last August.

With filming done, other actors have been sharing behind-the-scenes photos, including newcomer Valorie Curry, who plays the supe Firecracker.

"Officially de-Firecrackered. That's a wrap on season 4 of The Boys!" Curry wrote on Instagram, flipping the bird to the camera. "Congrats to the entire cast and crew on an epic season! Time to go sleep for a month."

Sign up for Entertainment Weekly's free daily newsletter to get breaking TV news, exclusive first looks, recaps, reviews, interviews with your favorite stars, and more.

Related content:

• The Boys star Jensen Ackles says he has a Soldier Boy cameo in Gen V spin-off
• Best of 2022 (Behind the Scenes): Brett Geddes, the pint-sized Termite on The Boys, gets his big break
• The Boys stars return in bloody first-look teaser for Gen V spin-off