In Batman vs Superman, Batman tells Alfred that

Doomsday is Kryptonian,

so he can be defeated with the kryptonite spear. How does Batman know that

Doomsday is Kryptonian?

  • Batman is a genius-level detective. It wouldn't take someone like that much time to connect the dots. I myself have deduced that since the Kryptonian ship was recently activated with strange electrical activity (most likely by Luthor), and given that there's been a lot of attention towards Superman from Luthor, and suddenly, this humongous and Super-strong beast pops up near the vicinity of the ship; the being is most likely Kryptonian.
    – Möoz
    Commented Aug 26, 2016 at 3:19
  • @Mooz I originally thought along those lines, but the timing is off: Batman knew all those things and still didn't realize Doomsday was Kryptonian until later, or he would have immediately went for the spear
    – Jackman
    Commented Aug 26, 2016 at 3:46

3 Answers 3


It seems to be a combination of things that lead to this realization: First, he knew the Kryptonian ship drained power from the city (as told to him by Lois Lane right after his fight with Superman). Then he learned from Alfred that there was a creature wreaking havoc in Metropolis. But from the timing of his realization, it appears the final clue was that Doomsday had the ability to shoot lasers from his eyes, an ability that only the Kryptonians (Superman and Zod) had ever demonstrated. Right after being shot at by Doomsday he seems to suddenly put it all together - because that's when he thinks out loud to Alfred that it's Kryptonian and he must go back to Gotham for the spear - if he had already deduced it earlier he would have immediately headed for Gotham before approaching Doomsday.

  • 4
    Aside from Superman, Zod also showed the ability to shoot lasers out of his eyes (right before he died). Which only strengthens the idea that it's a Kryptonian thing. Commented Mar 23, 2017 at 16:37
  • @DaaaahWhoosh youre right I'll include that in the answer
    – Jackman
    Commented Mar 28, 2017 at 20:31

During the movie, they know that Doomsday is actually General Zod. Since everyone knows Superman is Kryptonian it makes sense that Batman would know that Doomsday's weakness is also Kyrptonite.

Ancient Kryptonian deformity. The blood of my blood. Born to destroy you. Your Doomsday. Now God is good... as dead.

On top of that, Batman as a great detective knows,

  1. Its not from earth.
  2. It mirrors supermans power.
  3. Luthor had control of the Kryptonian ship
  4. the monster emerged from said ship.
  • 2
    At what point is it made clear that everyone knows he's Zod?
    – Jackman
    Commented Aug 26, 2016 at 3:47
  • @Woody heres the quote from lex luthor
    – Himarm
    Commented Aug 26, 2016 at 3:52
  • Batman wasn't present, and did not communicate with Superman until later
    – Jackman
    Commented Aug 26, 2016 at 4:00
  • Also, he should have gone for the spear immediately if he knew at that point
    – Jackman
    Commented Aug 26, 2016 at 4:01
  • Good grief, what abysmal dialogue... Commented Mar 28, 2017 at 21:25

Keep in mind that Batman had a copy of Luthor's computer data. This included not only his information on meta-humans, but presumably also his data on the Kryptonian ship and General Zod's body. At the time of Doomsday's appearance, Batman knew the following:

  • Luthor was experimenting with Kryptonian technology (the ship)
  • Luthor was experimenting with Kryptonian biology (Zod's corpse)
  • Luthor's research was advanced enough to synthesize the Kryptonite (which is where Batman got it from, in fact)
  • Doomsday emerged from the Kryptonian ship's crash site, not the LexCorp building (as noted by the news reporter in the quote below), only minutes after the ship suddenly showed activity
  • Doomsday exhibited the same powers as Superman, proving impervious to both ballistic weapons and missiles when the military attacked

REPORTER: This thing emerged from the Kryptonian crash site just moments ago.

Given Batman's skills at deductive reasoning, it's not unreasonable to assume that he could connect these facts with the sudden appearance of the monster from an otherwise dormant ship. Here's the scene you're referencing, where Batman announces Doomsday is Kryptonian. It's immediately after the monster fires his heat vision at the Batwing when Batman makes the connection:

BATMAN: Alfred. It's Kryptonian... only Kryptonite weapons can kill it.

ALFRED: It might, if you have any left.

BATMAN: [checking on the weapons] I've only got one round left. Wait... the spear. Alfred, the spear! It's pure kryptonite. It's back in Gotham. If I can penetrate the skin, the spear will kill it.

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