1. Chiyo, Gaara's grandmother and a skilled puppeteer, was also a medical ninja. She used a forbidden medical technique to revive Gaara by injecting her chakra into his body, sacrificing her own life in the process.

2. Nagato, the leader of the Akatsuki, had the Rinnegan implanted by Madara. He summoned the Gedo Statue but grew weak when his chakra was depleted, so he created the Six Paths of Pain to aid him.

3. The Third Raikage was a formidable Hokage who battled the Eight-Tails and cut off one of its horns, showcasing his strength. During the Fourth Great Ninja War, he fought against tens of thousands of allied forces to protect his teammates, ultimately dying when his chakra was exhausted.

4. Lastly, Kakashi, Naruto's teacher, and the Sixth Hokage, frequently depleted his chakra using Kamui in his fight against Pain. To let Naruto escape, he used Kamui to teleport one of Pain's bombs, sacrificing his life when his chakra ran out. However, Nagato successfully revived him.