Allen Walker (アレン・ウォーカー, Aren Wōkā) is the protagonist of the D.Gray-man manga and anime series created by Katsura Hoshino. He was created from the female protagonist of the D.Gray-man's predecessor Zone; Hoshino lengthened the female character's hair to create Walker's design.

In the series, Walker joins the Black Order as an Exorcist, a soldier able to use the weaponized form of Innocence to destroy the Millennium Earl's Akuma. He fights against the Earl and his followers, the super-human Noah Family, to prevent their plan to destroy the world. He is also the prophesied Destroyer of Time believed to be the only one able to defeat the Earl. However, Walker is also Neah, the 14th Noah who was killed for betraying the Earl. Eventually, the Order revokes Walker's Exorcist status and treats him as a Noah, forcing Walker to flee the Order.

Walker appears other media relating to the franchise, including two video games and two light novels. His character has been very popular with the D.Gray-man readers, usually ranking first in the series' popularity polls. Reaction to Walker's character is generally positive. Several pieces of merchandise have been released in Walker's likeness, including a plush doll, a figurine, clothing and cosplay pieces. His character design is highly praised, as well as his difference from a typical shōnen protagonist.