In Japanese, Gengar has been voiced by multiple actors which include Kiyonobu Suzuki, Kōichi Sakaguchi, Nobutoshi Canna and Yasuhiro Mamiya.

[10] In these games and their sequels, the player assumes the role of a Trainer whose goal is to capture and use the creatures' special abilities to combat other Pokémon.

[15] In another interview stating that while it's designed to be a ghost and a little bit scary, he also saw its character as "funny" and felt it had the necessary elements for a Pokémon, utilizing simple shapes and a "charming" grin he quite liked.

[16] Standing 4 ft 11 in (150 cm) tall,[17] Gengar has a round purple body, short arms and legs, two red eyes, and a perpetual toothy grin.

Gengar spends much of the game causing trouble, even convincing the village to exile the hero, blaming him or her for the natural disasters.

[38][39] Frequently used in Halloween-themed promotions related to the franchise,[40] Gengar has been featured on multiple items of Pokémon merchandise and media since their introduction, such as a Squishmallow plush,[41] Gengar-themed chocolate chip Eggo Waffles,[42] and a Gengar-themed bed, produced by Bandai, which utilized the species' extra long tongue and wide mouth as cushioning.

[46] The book Pikachu's Global Adventure: The Rise and Fall of Pokémon noted the species was particularly popular with older male children who tend to be drawn to "tough or scary" characters.

[47] Cian Maher, writing for USA Today described it as an instantly recognizable symbol of the franchise and "one of those precious few 'mons that is unanimously loved by Nintendo and fans alike".

[48] Robert Grosso of TechRaptor praised their "sinister" design as one of the best of the original Pokémon games, feeling its Cheshire Cat-like grin and red eyes embodied the series more "malign nature".

He further called it "simple done right", noting a resemblance to a human shadow and an iconic face, which he felt helped fit what he saw as a doppelgänger design philosophy.

[51] USgamer's Kat Bailey described it as the "Joker of the Pokémon universe: apt to turn on you at any moment", noting while its simplistic design and smile promised mischief, its Pokédex entries hinted at darker intentions.

[52] Kotaku's Kenneth Shepard noted that while it was not a personal favorite of his, he agreed with the notion that it made an impact on the series, with Gengar serving as the blueprint for Ghost-type Pokémon that would be added later to the franchise.

[53] Meanwhile, TheGamer's editor in chief Stacey Henley described it as "wonderfully expressive", arguing that the species was charismatic and had enough personality to be able to be the star of their own standalone game.

Citing its portrayal in New Pokémon Snap, where the species was demonstrated with more depth and allowed to play the role of a prankster with their powers, she felt it would be well suited for "the darker, gothic settings" not seen enough in the franchise.