Agent X-13

Agent X-13 is a wartime spy character who debuted in the very first issue of Captain America Comics, operating in the patriotic, World War II-era espionage milieu that defined Marvel's Golden Age roots alongside Captain America and Bucky.

Few characters can claim a more legendary birthplace than Agent X-13, who made their debut in the very first issue of Captain America Comics in 1941 — one of the most celebrated and collectible single issues in the entire Golden Age canon, brought to life by the iconic duo of Joe Simon and Jack Kirby. Sharing those historic pages with Captain America, Bucky, and even a fictional Franklin D. Roosevelt, Agent X-13 is woven into the very fabric of Marvel's wartime origins. With appearances stretching across reprints and tributes all the way to 2021, this figure has quietly endured as a footnote in one of comics' most storied franchises. For Golden Age devotees and Captain America completists alike, any character present at that legendary first issue is worth a closer look.