Who Killed the Test Subject Titans?

Direct Answer to the Core Question

In Attack on Titan, the test subject titans — the Warriors introduced in Marley’s Warrior program — are not killed by a single attacker in one event. Instead, their fates vary by path: in the main timeline, most are killed during the Raid on Liberio and the subsequent battles against the Beast Titan and Cart Titan. In the Paths, future memories show alternate deaths and outcomes. The canonical truth combines the Warriors’ own decisions, Marleyan tactics, and Eren’s actions through the Founding Titan. The test subject titans ultimately die in combat, with Pieck’s Cart Titan and Zeke’s Beast Titan playing decisive roles in their destruction.

What Are Test Subject Titans?

Test subject titans refer to Eldian captives and Subjects of Ymir used by Marley and other nations to develop Titan abilities, strategies, and the Warrior program. These individuals are transformed into Titans for military research and combat training. Their bodies are used to study Titan biology, hardening, and inheritance. In-story, the term often describes early Titans experimented on before the Nine Titans were consolidated. Understanding this context is essential to tracing how and why these titans are targeted and killed across the series.

The Warriors and Their Canonical Fates

The Warrior unit consists of Reiner Braun (Armored Titan), Bertolt Hoover (Colossal Titan), Annie Leonhart (Female Titan), and Pieck Finger (Cart Titan), with Zeke Yeager (Beast Titan) serving in a related but distinct role. Each follows a distinct path shaped by allegiance, trauma, and strategy. Their test-subject origins inform their roles as both weapons and individuals caught between Marley and Paradis. Below is a summary of their canonical status and how their stories culminate.

Notable Warriors and Key Moments

Key Battles Where Test Subject Titans Die

The deaths of the test subject titans occur across several major arcs, primarily during the Marley arc and the climax on Paradis. These confrontations involve the Scout Regiment, Marleyan forces, and allied Titans. The outcomes are shaped by strategy, Titan hardening, and the environment. The following breakdown highlights pivotal engagements and who delivered or received the fatal blows.

Raid on Liberio (Anime: Season 4, Manga: Chapters 95–105)

• Bertolt Hoover (Colossal Titan) is killed by Armin, who inherits the Colossal Titan and uses its steam to incinerate Bertolt. This is one of the most direct and canonical deaths among the test subject titans.
• Reiner Braun (Armored Titan) is critically injured but survives; he is later rescued and healed.
• Pieck Finger (Cart Titan) is incapacitated and captured but not killed during the raid.

Battle at Fort Slava (Anime: Season 4, Manga: Chapters 95–107)

• Zeke Yeager (Beast Titan) is targeted by the Scout Regiment and decapitated by Levi, leading to his canonical death.
• While Zeke is not a standard test subject titan, his role in the Warrior program and Marleyan experiments places him among the tested Titans.

Shiganshina District and the Final Battle (Anime: Season 3–4, Manga: Chapters 80–109)

• The Armored Titan suffers repeated damage but survives until retreat; later, in the final war, it is incapacitated and not killed in direct combat.
• The Female Titan is encased in crystal by Levi and later rescued; canonical death is not confirmed.

The Paths, Memory Manipulation, and Alternate Outcomes

The Paths realm introduces memories of possible futures, showing alternative deaths and timelines for the Warriors. These visions are not canonical outcomes but are used to pressure characters during the Rumbling and allied confrontations. In these sequences, test subject titans appear killed or subdued in various ways, reflecting the psychological and narrative weight of choice. The canonical world, however, follows the events of the main story where deaths are limited to Bertolt and Zeke, with others surviving in varied conditions.

Conclusion: Summary of Who Killed the Test Subject Titans

In summary, the test subject titans die under specific, canonical circumstances primarily during large-scale warfare. Bertolt Hoover is killed directly by Armin via the Colossal Titan’s steam. Zeke Yeager is executed by Levi after his defeat. Reiner and Annie are severely injured but survive, while Pieck is captured and repurposed. No single person is responsible for all the test subject titans; instead, their fates are distributed across battles, Titan inheritances, and strategic decisions. Their stories illustrate the high cost of the Warrior program and the human consequences behind Marley’s Titan experiments.