Last night on ABC’s “Castle,” Nathan Fillion returned as his old beloved “Firefly” character Captain Mal for a one night special surprised appearance.

Fillion’s character, Richard Castle, wore a Halloween costume and claimed that he was a mere “space cowboy.” But any real geek would have recognized that he was indeed, Captain Malcolm Reynolds of “Firefly/Serenity” fame. A character named #18 in TV Guide’s “Greatest Sci-fi legends” list in 2004.

Watch the clip below and try to hold back nostalgic tears: