Beheeyem is a brown extraterrestrial Pokémon with an oblong head that features depressions on both sides. It has black, symmetrical lines going down the front of its head. Under the rim of its head, there lay two green eyes with small black pupils. It has a lighter brown "collar" and four dots on its chest of the same color. Beheeyem's arms have three finger-like digits: one red, one green, and one yellow. It has a rim underneath its main body, under which are two small legs. It communicates by flashing its multi-colored fingers. Beheeyem can change the memories of its opponents, being able to erase or even rewrite them.
- Beheeyem and its pre-evolution Elgyem are the only species that can have Telepathy without it being their Hidden Ability.
Beheeyem is based on greys, one of the more popular kinds of alien. Judging from Elgyem's Pokédex entry, it and its evolution may also be based on the Area 51 alien conspiracies or the Roswell incident. Additionally, Beheeyem's design resembles a person wearing a hat and trenchcoat and is likely based on stereotypical spies, shady figures, "Men in Black", or government agents in connection with alien sightings. The colored dots on its hands resemble the colorful faces of the invaders in the 1953 War of the Worlds film; the aliens in the film had green, blue and red dots just like Beheeyem's Shiny coloration. Considering its species names, physical appearance, and powers, it may also be based on a brain.
- Beheeyem is a corruption of the abbreviation BEM ("bug-eyed monsters"), an old-fashioned term used to refer to extraterrestrials. Its Japanese name, Ohbem, may be a combination of orb and BEM (pronounced as a single word in Japanese). Oh may also refer to 大 ō (large) and bem may also refer to beam (referencing tractor beams from UFOs).