A full Vayne skin gallery, plus the practical point: some skins change the silhouette enough to matter in a fight.
Before the cosmetics: Vayne is a marksman at 550 attack range whose job is to deal damage every second of a fight from behind people who can absorb one.

Vayne has 21 skins, excluding chromas. The art below is the in-client splash.
Skins change no numbers. They are not therefore free of consequence — a skin that alters the silhouette or recolours an ability changes how quickly an opponent reads what you just cast.
That cuts both ways, and it is the honest reason some players keep the base skin on champions they take seriously.
Vayne ruthlessly hunts evil-doers, gaining Move Speed when moving toward nearby enemy champions.
Vayne tumbles, maneuvering to carefully place her next shot. Her next attack deals bonus damage.
Vayne tips her bolts with a rare metal, toxic to evil things. The third consecutive attack or ability against the same target deals a percentage of the target's max health as bonus true damage.
Vayne draws a heavy crossbow from her back, and fires a huge bolt at her target, knocking them back and dealing damage. If they collide with terrain, they are impaled, dealing bonus damage and stunning them.
Readying herself for an epic confrontation, Vayne gains increased Attack Damage, Invisibility during Tumble, reduced Tumble cooldown, and more bonus Move Speed from Night Hunter
Shauna Vayne is a deadly, remorseless Demacian monster hunter, who has dedicated her life to finding and destroying the demon that murdered her family. Armed with a wrist-mounted crossbow and a heart full of vengeance, she is only truly happy when slaying practitioners or creations of the dark arts, striking from the shadows with a flurry of silver bolts.
Skins are tied to the account, not to you. Anything bought on a smurf stays on the smurf — worth knowing before spending real money on one.
Full Vayne page — abilities, stats and every skin →