If you hadn't already guessed, Mon-El, Miss Martian and the Guardian are only the beginning of "Supergirl's" deep dive into the DC Comics library this season.
As confirmed by the newly released synopsis for The CW drama's Nov. 21 episode, Cyborg Superman will make his debut in "The Darkest Place." That's perhaps not entirely as a surprise, as David Harewood's used the name Hank Henshaw -- Cyborg Superman's identity in the comic books -- before being revealed later in Season One to be the classic DC hero J'onn J'onzz (aka the Martian Manhunter). Fans have long speculated Cyborg Superman would eventually appear in one form or another.
In DC comics, Henshaw was a crew member of a doomed NASA space shuttle whose consciousness was transferred into the LexCorp mainframe following an accident that claimed his life as well as the lives of his wife and colleagues. Becoming delusional and paranoid, he blames Superman for the accident, so when the Man of Steel was killed by Doomsday, Henshaw constructs a virtually identical body so he can pose as the superhero in order to destroy his reputation.
We'll have to wait to see just how Cyborg Superman will be depicted on "Supergirl." Fans have already theorized that Dean Cain, who played Kara's late foster Jeremiah Danvers, might somehow return as the supervillain. However, we probably shouldn't rule out the possibility that guest star Tyler Hoechlin, who's already appeared as the Man of Steel, could pull double- -- or is that triple? -- duty on the series.
Here's the official synopsis for "The Darkest Place":
IT’S SUPERGIRL VS. CYBORG SUPERMAN — While Guardian (Mehcad Brooks) tries to clear his name after being accused of a murder committed by another vigilante, Supergirl (Melissa Benoist) heads out on a solo mission to rescue Mon-El (Chris Wood) who has been captured by CADMUS. While fighting to free Mon-El, Supergirl comes face to face with Cyborg Superman. Glen Winter directed the episode written by Robert Rovner & Paula Yoo (#207). Original airdate 11/21/2016.
Airing Mondays at 8 p.m. ET/PT on The CW, "Supergirl" stars Melissa Benoist in the title role, with David Harewood as Hank Henshaw/Martian Manhunter, Mehcad Brooks as Jimmy Olsen, Chyler Leigh as Alex Danvers and Jeremy Jordan as Winn Schott. The series also features guest appearances by Calista Flockhart as Cat Grant, Chris Wood as Mon-El, Floriana Lima as Det. Maggie Sawyer and Tyler Hoechlin as Superman.