"Castle" season 8 will be bringing back one iconic guest star - Adam Baldwin's Detective Ethan Slaughter.

According to Entertainment Weekly, details on Slaughter's return are being kept under wraps, but he will be appearing in an episode that is slated for early release in the season. Some are guessing that he might be working with Rick Castle (Nathan Fillion) on a case now that Castle's wife, Kate Beckett (Stana Katic) is the captain of the 12th Precinct, aside from a new series regular Hayley Shipton (Toks Olagundoye).

Slaughter first appeared in "Castle" season four in the episode entitled "Headhunters." He is a rough cop that employs crude methods to get the job done. Slaughter is known for sporting a trademark brown coat, which the actor even got to take home after the episode wrapped up, and he wore it when he appeared in Comic Con 2012 and Nerd HQ.

Baldwin and Fillion both worked together in the now-cancelled show "Firefly" as Jayne Cobb and Malcolm Reynolds, respectively. Baldwin's characters Cobb and Slaughter are both described as violent, unprincipled, and even dangerous not to his enemies, but sometimes even his allies.

Prior to "Firefly," Baldwin appeared as the fanatical priest of evil Caleb in Joss Whedon's earlier work "Buffy the Vampire Slayer," which starred Sarah Michelle Gellar. The actor also played demonic lawyer and emissary of the Senior Partners, Marcus Hamilton, on "Angel," which starred David Boreanaz.

He has also some meaty parts in the "X-Files" series as the super soldier Knowle Rohrer, and he also became Animal Mother in "Full Metal Jacket" and Colonel John Casey in "Chuck."

One of his longest running works is "The Last Ship," a series he has been co-starring with Eric Dane with since June 22, 2014.

The whole cast and crew of "Castle" are really excited for fans to see what happens in the new season, including lead star Katic. While they were preparing for the new episodes, the actress wrote on her Twitter account: "Had a great mtg w @AlexiHawley & @OldManWinter14 about S8! (Nail-biter) Love #Castle cast&crew. Looking forward to playing together again."

Alexi and Hawley and Terence Paul Winter took over being showrunners from David Amann, while series creator Andrew Marlowe and his writer slash producer wife Terri Miller will no longer be working on the show as well.

"Castle" will return on Monday, September 21 at 10 p.m. ET on ABC.