SPOILER WARNING: This article contains major spoilers for “In Search of Lost Time,” the latest episode of Supergirl.
Supergirl just introduced an obscure character from Martian Manhunter's past. In "In Search of Lost Time," the latest episode, J'onn's father M'yrnn namedropped Zook, an imp from the fifth dimension.
In the beginning of the episode, M'yrnn learned to play charades with J'onn, Kara, Alex, James and Winn. However, his Martian abilities -- like shapeshifting and mind-reading -- gave him a certain advantage over the other players. J'onn playfully accused M'yrnn of cheating, only for his father to recall how J'onn used to cheat at a Martian board game as a child and blame it on his imaginary friend Zook.
Zook is, of course, a character from DC Comics' mythology. Debuting in 1963's Detective Comics #311, Zook was one of four creatures accidentally transported to Earth in a spacewarp. When an off-duty cop spotted them, she called up Detective John Jones, who showed up to investigate as his alter ego Martian Manhunter. Martian Manhunter was able to send Zook's compatriots back to their proper world, but accidentally left Zook behind and decided to keep him as a "pet." However, Zook -- who possesses a few powers of his own -- soon learned English and became J'onn's crime-fightning partner instead.
It's very unlikely that Zook himself will turn up on the show, as the episode made a few jokes at his expense. However, the mention of Zook is a nice nod to a rather unusual part of Martian Manhunter's comic book history.
Airing Mondays at 8 p.m. on The CW, Supergirl stars Melissa Benoist as the Girl of Steel, David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen, Chyler Leigh as Alex Danvers and Jeremy Jordan as Winn Schott, with appearances by Calista Flockhart as Cat Grant and Tyler Hoechlin as Superman.