- For the episode, see "".
- For cases of individuals fulfilling the same name or role as others through the multiverse but without looking the same, see Multiverse counterpart.
- "And these other Earths, 3, 4, 5, to infinity, all of them, are nearly identical to ours. And they all exist at the same time, giving us endless alternatives to what we have here. For example, the Joe West on Earth-2, your doppelgänger, he might not be a detective. He could be a Nobel Prize-winning physicist. And you, the Barry Allen here is the Flash, but over there, he could be an electrician."
- —Martin Stein[src]
Conceptually, a doppelgänger is an individual that looks the same as another. In the multiversal sense, a doppelgänger typically refers to an alternate universe version of an individual. In some cases, these doppelgängers may also share identical roles/occupations on their respective Earths, such as Earth-38's James Olsen and his Earth-X counterpart having similar-looking suits that they wear when operating in the field as vigilantes. Doppelgängers do not always share the same name or appearance. For example, Barry Allen of Earth-90 looks like the Henry Allen of Earth-1 while Henry's Earth-3 doppelgänger is named Jay Garrick. Furthermore, the Clark Kents of Earth-38, 96, and 167 all have different appearances; in the case of Earth-96 Clark Kent, he looks exactly like Ray Palmer from Earth-1. Also, Lois Lane on Earth-167 looks exactly like Alura Zor-El on Earth-38. Even if doppelgängers look alike, they don't always share the same birthdate, as evidenced by Thea Queen of Earth-1 being nine months and three days younger than her late Earth-2 counterpart. Doppelgängers can also bear different genders on some Earths, such as Earth-Prime's Brainiac 5 and Earth-TUD16's Brainiac 5. Additionally, some people may not have doppelgängers on certain Earths due to extenuating circumstances.
- After Crisis, it seems that the multiverse will not allow multiple versions of one person to exist on one Earth due to neurological degeneration, as the good Beth Kane was dying as a result of being near her Earth-Prime self. However, that did not happen to Al and his doppelgänger, the Brainiac 5s, or Winn and his evil counterpart.