[[Eren Yeager]] in his spinal state [spoiler]during the final battle of [[Shingeki no Kyojin]][/spoiler].
[spoiler]
Prior to [[Eren Yeager|Eren]]'s transformation into the founding titan and starting the rumbling, [[Gabi Braun]] shot his head off and it touched [[Zeke Yeager]] at the same time, triggering the transformation. During it, his body was not regenerated and was instead simply attached to his titan with its spine.
[/spoiler]
spine eren