Heliolisk is a large bipedal reptilian Pokémon that resembles a frilled neck lizard. Its slender body is mainly bright yellow, with black patches on the top of its head, its frilled neck, its claws, its feet, and the tip of its tail. The tips of its neck frills are triangular and orange in color, and it has orange stripes around its legs.
When emitting electricity, it extends the frills on its neck, which flare up, resembling a sun-like shape.
No other Pokémon has same type matchup of electric/normal as Heliolisk and its pre-evolution Helioptile.
Heliolisk's name is directly based from the word "Helios" which means "sun" in Greek or Latinized Greek and "Basilisk"; which is a type of monster that resembles a serpents with limbs or a certain type of giant lizard.