She was a legendary Jedi Master during the final years of the Galactic Republic, maintaining a seat on the Jedi High Council during the Naboo Crisis. Notably, Yaddle was a member of the same enigmatic species as Grand Master Yoda.
Yaddle was present on the Jedi Council when Master Qui-Gon Jinn claimed he found a boy named Anakin Skywalker who believed to be the destined Chosen One. Yaddle and the Council tested the boy and found that he was incredibly gifted in the ways of the Force but close to the dark side. Qui-Gon later returned to Naboo and was slain by a Sith assassin. The Council left for Naboo to attend Jinn's funeral, but Yaddle and few others remained at the Jedi Temple.
Yaddle has devoted a lot of time to scholarly interests, and spends much time in the Jedi Archives. She has also been an active Jedi in the field. Yaddle's final mission was with Obi-Wan Kenobi and Anakin, when she sacrificed her life to save the people of the planet Mawan by using the Force to absorb a deadly biological weapon.
Yaddle was one of the few Jedi permitted to practice morichro. This ancient art enabled the user to rapidly slow down an opponent's bodily functions to the point of death.