There are many hair accessories in Lineage II. Unfortunately, not all of them had hair accessory textures created for the Ertheia race to wear.
I have compiled a list of hair accessories that can be worn by the Ertheia:
Academy Circlet
Adventurer Hat
AE Karm
Afro Hair
Angel Circlet
Antharas Slayer Circlet
AR Karm
Arrow-Pierced Apple
Artisan's Goggles
AU Karm
Bamboo Panda Hat
Bee Hat
Beetle Hat
Birthday Hat
Black Phantom Mask
Brown Bear Hat
Butterfly Hairpin
Castle Circlets
Cat Ears
Chapeau
Sweet Cheese Hat
Chic Gold Horn Cap
Chic Silver Chapeau
Chic Silver Horn Cap
Chicken Hat
Child's Hat
Circlet of Darkness
Circlet of Earthquake
Circlet of Flames
Circlet of Ice
Circlet of Ice Fairy Sirra
Circlet of Splendor
Circlet of Storm
Clownfish Hat
Coronet
Daisy Hairpin
Dapper Cap
Demon Circlet
Demon Horns
Draco Hat
Eyepatch
Fairy Antennae
Fancy Flower Hat
First Mate Hat
Fish Hat
Forest Forget-me-not Hat (Not the hairpin)
Frog Hat
Full Party Mask
Gatekeeper Hat
Gold Afro
Gold Circlet
Gold-rimmed Glasses
Graduation Cap
Gran Kain's Black Mask
Grasshoppper Hat
Halisha's Helmet
Halloween Monster Masks
Headphones
High-level Angel Circlet
Horn-rimmed Glasses
Ice Queen's Tiara
Iron Circlet
Jack O' Lantern Mask
Jester Hat
Laborer Hat
Ladybug Hat
Lindvior Slayer's Helmet
Little Angel Wings
Lord's Crown
Maid Hairband (Not the one from the maid outfit bundle)
Mask of Spirits
Medieval Party Mask
Metal Suit Hair Accessory
Monkey Hat
Monocle
Napoleon Hat
Noblesse Tiara
Outlaw's Eyepatch
Pagan Devil Circlet
Party Hat
Party Mask
Pig Hat
Pig Wrangler's Cap
Piggy Hat
Pink Afro
Pirate Hat
Pirate King Hat
Pirate's Eyepatch
Plastic Hair
Praying Mantis Hat
Puffer Hat
Purple Viking Circlet
Rabbit Ears
Raid Circlets
Red Flame Valakas
Red Party Mask
Refined Angel Circlet
Refined Black Feather Mask
Refined Brown Turban
Refined Cow Hat
Refined Devil Horn
Refined Jester Hat
Refined Medieval Party Mask
Refined Penguin Hat
Refined Romantic Chapeaus
Refined Shark Hat
Refined Skeleton Circlets
Refined Turtle Hat
Refined Wizard Hat
Refined Yellow Turban
Ribbon Hairband
Rocketgun Hat
Romantic Chapeau
Ruthless Tribal Mask
Samurai Hair Accessory
Santa Antlers
Santa Hat
Scholar's Hat
Sheep Hat
Shyeed's White Mask
Silver Circlet
Teddy Bear Hat
Territory Wars Circlets
Top Hat
Unicorn Horn Circlet
Uniform Hat
Valakas Slayer Circlet
Valkyrie Circlet
Vesper Noble Mask
Vigilante Hat
Warrior's Helmet
Watermelon Hat
Wedding Veil
WiFi Helmet
Wings of Destiny Circlet
Wizard Hat