Zekrom is a large, black draconian Pokémon that seems to share its theme with its counterpart, Reshiram. It has piercing red eyes and dark gray to black skin that seems to be armour-like. It has a large, generator-like tail and long mane that ends in a tip, both seem to glow in an iridescent blue color. It also has a set of black wings behind its three-clawed arms.
Zekrom's name comes from the Japanese word "kuro" which means "black", referencing its color.
It was first revealed on the official Pokémon website on May 28, 2010 along with Reshiram. This makes the two the first Pokémon simultaneously revealed worldwide.
Zekrom has similar traits of those found in Zapdos.
Both are a part of a Legendary Trio.
Both are a part of a Fire-Electric-Ice trio.
Both are the Electric type in their trio.
Both of the names of these legendary Pokémon start with "Z".
Zekrom is the first Pokémon to have a type combination of Dragon and Electric. It is so far the only Pokémon to have this type combination.
Both Zekrom and Reshiram's tails are round and large, with a small point at the end, like a jet engine.
Zekrom, besides Grass-form Rotom, is the only Pokémon to have a double resistance to Electric-type moves.
Zekrom, along with Reshiram and Kyurem, is part of the Tao Trio. Zekrom embodies mechanism.
The roar used for Zekrom is Megaguirus', a monster from the Godzilla franchise. In Movie 14, though, he had the roar of Baragon, another monster from the same franchise. Reshiram received Megaguirus' roar, as a result.
Although Zekrom's pupil is white at the beginning of In the Shadow of Zekrom it had a glowing light blue eye.
Zekrom also appears in a Dream World minigame; if the WIFI Zekrom from the Black version game is brought over to the Dream World, in the special home, Victini appears, and afterwards, at the intro of that minigame, Victini tries to break the barrier, but its attack is useless, and so the player has to ask his/her WIFI Zekrom for help by collecting power ups. The finishing move is Zekrom using a electrical attack to blow up the barrier.
Zekrom's move, Bolt Strike, is Thundurus' species.
Zekrom appears to be based off of the Yu-Gi-Oh! monster "Red-Eyes Black Dragon" as both are black dragons with red eyes.
In Hyperdimension Neptunia Victory, a DLC weapon for Rom, the Staff of Truth, resembles Zekrom after fusing with Kyurem.