An Attack on Titan necklace is a stylish accessory inspired by the popular anime and manga series "Attack on Titan" (Shingeki no Kyojin). These necklaces typically feature symbols, emblems, or characters from the series, such as the Scout Regiment emblem, the Wings of Freedom, or iconic characters like Eren Yeager, Mikasa Ackerman, or Levi Ackerman. 

They are often crafted with high-quality materials such as metal or alloy and may include intricate details to appeal to fans of the series. Attack on Titan necklaces are popular among anime enthusiasts who wish to showcase their love for the show and its characters in a fashionable and meaningful way.