Jessie's Arbok is a poison-type Pokémon once owned by Jessie.
Jessie's Arbok was most likely Jessie's first Pokémon. She got it as a Ekans for her birthday. Eventually it evolved into an Arbok because Jessie wished desperately for it to. It was later released to protect a group of Ekans from a Pokémon Poacher. When Jessie told it to stay behind and protect the Ekans while she, James and Meowth held off the Pokémon Poacher, it started crying as did James's Weezing.