The Star Rod is an important item in the Kirby series, first appearing in Kirby's Adventure for the NES. In the series, Kirby used to battle Nightmare and thus save his planet. While it does give Kirby an added ability, it is not commonly considered a copy ability seeing that the player does not have to gobble up an enemy to earn this power.
In the games that it appears in, it is usually used in the end of the game. The Star Rod has as of yet only appeared in two Kirby games, including Kirby's Adventure and Kirby: Nightmare in Dream Land. It also appeared in all three Super Smash Bros. video games as an item, which include Super Smash Bros., Super Smash Bros. Melee, and Super Smash Bros. Brawl.
The Star Rod also appeared in the final episode of Kirby: Right Back at Ya!, "Fright to the Finish", where, like in the games that it appeared in, Kirby uses it to ultimately defeat Nightmare. Unlike in the games, it is shown here that Kirby is able to produce the Star Rod by swallowing his own Warp Star.