Legendary Pals
Two answers, both from the game. 6 Pals carry the passive skill Palworld itself calls Legend — that is the strict list. The top of the rarity scale is wider at 17. Most lists online pick one of these silently; here is both, so you can tell which one you were asking about.
The 6 with the Legend trait
These carry a passive skill named Legend in the game files — a flat boost to attack, defence and movement that no other Pal gets. If someone says “the legendaries”, this is the list they mean.
Neutral
Dark
Ice
Water
DragonThe rest of the top rarity tier
Rarity 10 and above, without the Legend passive. Tower bosses and the hardest alphas live here, which is why the two lists disagree — they are rare, but the game does not call them legendary.
Ground
Fire
Rare, but not in the Paldex
Dragostrophe, Moon Lord, True Eye of Cthulhu sit at this rarity but carry no Paldex number — event and raid-only rows, which every listing on this site leaves out so the Paldex count stays honest. They are named here because at this tier, quietly dropping them would be the misleading choice.
Catching them
Legendaries have the harshest capture multipliers in the game, and the multiplier is a stated number rather than a feeling — the capture rate calculator works out what a given sphere actually gives you against one. Several also breed, which is usually faster than farming the spawn.
Why two lists
Palworld does not ship a flag called “legendary”. It ships a passive skill named Legend and a numeric rarity, and those two do not select the same Pals. Rather than pick one and present it as the answer, both are here with the criterion stated — everything on this page is a value in the files, not a judgement about what counts.
Extracted from Palworld’s game files on (build 4797106687).