Pirate

One completed pirate invasion is the entire requirement, plus the usual empty house. The interesting part is that neither check asks whether the world is in hardmode. The summoning item comes out of a hardmode world, but items travel between worlds, so carrying a Pirate Map into a fresh save lets you run the event and install him absurdly early. Two other residents share that loophole, and it is the standard way people get a vendor tier ahead of schedule.

The Cannon is a placed weapon you aim and fire by hand, and it is the only genuinely combat relevant thing he stocks. Built into an arena wall facing wherever enemies funnel in from, it does real work during invasions and any other event where a crowd walks toward you in a line. Cannonballs are cheap enough to keep a chest of them standing next to the gun and never think about the cost again. The catch is that firing it takes your whole attention, so it suits a second player, a lull between waves, or a defended position you are not personally standing in.

The outfit and the Sail are decoration and nothing more. The Parrot Cracker is a pet that costs a small fortune and only appears while he is standing at the ocean, so it is a deliberate expedition rather than an impulse buy. The Jellyfish Block shows up only in a graveyard. The Bunny Cannon is a joke variant parked behind three separate conditions at once: hardmode, a Party Girl in town, and a mechanical boss dead. Like most vendors he will also sell the pylon for whichever biome he is happily settled in, which is usually the most valuable thing on the list.

He shoots at nearby enemies with a cannon of his own that alternates between bullets and cannonballs, which is more firepower than most of the town can manage. Housing him somewhere exposed, an ocean outpost or an arena edge, is much less of a death sentence than it would be for a defenseless resident, and he keeps working through an invasion rather than cowering in a doorway.

Nearly every name he can be given points at a real or fictional captain, with one Star Trek pun hiding among the historical ones. Shimmer turns him into a ghost, a nod to ghost ships, and the change alters his death sound as well as his sprite. It also leaves him looking a lot like the skeletal thing that appears when you kill a pirate captain. He is fond of the Angler in a way nobody else in town is, and he shows up in the credits trying to warn the boy off using a truffle worm for bait.