Jaga (voiced by Earl Hammond in the original series, Corey Burtonin the 2011 series) is also known as "Jaga the Wise" and is based on the jaguar. This elder warrior was once regarded as the greatest of all Thundercats by Lion-O himself. In his youth, Jaga was the Lord of the Thundercats, and rescued a young Hachiman from being trapped in the Jade Dragon (which later became a part of the Treasure of Thundera). An adviser and protector of the Lord's family, Jaga wielded the "Sword of Omens" and was a formidable fighter in combat. After Claudus was blinded Jaga became the main guardian of the Eye of Thundera, the Sword of Omens, and the Treasure of Thundera. It was Jaga who gathered the nobles of the Thundercats to escort Lion-O and the Eye of Thundera to safety, but did not survive the trip to Third Earth as he volunteered to pilot the damaged ship while the others slept. Because of this, Jaga died of old age. However, Jaga does reappear on Third Earth as a ghost (seen only by Lion-O at first) to guide him in his lessons and adventures. At times, he appears before the other Thundercats as well such as when facing down Grune the Destroyer's ghost and when the Thundercats need to rescue their fellow Thunderians. Jaga's physical body does reappear at one point during the original series in the episode "The Astral Prison" where he was trapped in another dimension, prompting Lion-O to travel there to rescue him from being held captive by an evil inhabitant of said dimension. His fate as a physical living entity after this was never revealed, but his spirit form continued to appear throughout the series.
In the 2011 series, Jaga serves as head of Thundera's clericwarriors, possessing a knowledge of ancient secrets, superhuman speed, projecting lightning from his staff. In his prime, he used the "Sword of Omens" in an epic duel against Ratilla. At the start of the series, Jaga sacrifices himself to ensure Lion-O and his group escape. This resulted with him being tortured into revealing the location of the "Book of Omens" to Mumm-Ra, though doing his best to resist the villain's magic when sealed within a lantern, eventually his free will wavers along with his physical form. Though Jaga destroys the lantern that was keeping his soul intact to save Lion-O from Mumm-Ra, his soul took residence within the Book of Omens and becomes Lion-O's guide. In the 2-part "The Trials of Lion-O" Pt. 1, Lion-O encounters Jaga in the entrance to the Spirit World. Jaga tells Lion-O of the challenges he must undergo to gain a second chance in life. But when he failed the final test, Jaga allows Lion-O to return to the living long enough to save the other ThunderCats though it would exile Lion-O's soul to Limbo by sunrise. However, once saving his friends, Lion-O learns from Jaga that it was actually a test like the other challenges and allows Lion-O to remain among the living.