Walky is a regular enemy in Kirby's game series. It is a living, sentient, dangerous microphone that can't carry a tune for its life. It is designed to look like a traditional stage microphone. Because it is hinged between its two halves, it is able to fire out amplified sound waves. It commonly attacks by shouting a terrible cacophony as it trudges along. Walky, despite its name, is actually unable to walk in earlier games, nor is it even truly personified in some games.
Walky also appears as a trophy in Super Smash Bros. Brawl.
According to Walky's Trophy in Brawl, it first appeared in Kirby's Dream Land. In this game, Walky is nothing but a mere item (and not a true being). In fact, this item does no harm to Kirby- it's actually a big help. If Kirby spits it out after inhaling it, Walky emits a booming blast of sound KOing all enemies on screen.
This is perhaps the basis for the real Mike ability that would appear in following games.
Paint Roller draws Walky as one of his drawings. It simply trots along until it walks right off screen. Rather than emitting a tasteless tune like it usually does, the drawn Walky just walks away quietly, hinting that this version of Walky is actually incapable of making any sounds. When inhaled though, it gives the Mike ability. Because the Mike ability can defeat Paint Roller almost instantly, it rarely gets drawn.
Kirby Super Star was first to use a truly-personified microphone for Walky's design (one that wasn't an enchanted drawing). It is also the first game to use Walky's current design. Super Star is often considered by fans to be Walky's true debut. Walky rarely shows up on levels, strolling about. Occasionally, it stops to cry out a terrible tune. This sends forth three bad notes, one straight forth and the others diagonally forward. On rare occasions, it will yell out the tune, but no notes will come out, causing him to run back and forth, jumping around occasionally. It gives the Mike ability when eaten again.
Walky appears as an obstacle in this game. It is seen singing quietly to itself on the track, doing nothing to harm Kirby. When inhaled, again, it gives the Mike ability.
Walky is portrayed differently in the anime. When Kirby swallows him and copies his ability, Kirby can use Mike Kirby more than the games' limit of three times. The effect is so destructive, Walky is the only monster who survives and runs away in fright after Kirby spits him out on top of the rubble that was Castle Dedede.