Jedi Master Oppo Rancisis was one of the last Jedi Masters to serve on the Jedi Coucil before it was destroyed during the Clone Wars. As a Thisspiasian, Jedi Master Rancisis exhibited the unique set of physical characteristics common to his species, which including a prolific beard, four arms, and a long, serpentine tail. Oppo also descended from the royal monarchy of Thisspias and inherited the throne as the planet's Blood Monarch. However, Master Rancisis abdicated his position remain with the Jedi Order. As a Jedi, Oppo was trained by Jedi Master Yaddle and eventually attained the rank of Jedi Master. As a Master, Oppo earned a seat on the Jedi Council, a position he held for nearly seventy years. Jedi Master Rancisis also became one of the most skilled users of Malacia, a Force-ability that allowed its user to inflict powerful feelings of dizziness and nausea in one's enemies without leaving lasting physical damage.

Jedi Master Rancisis was also a highly skilled battle strategist and was one of the prominent practitioners of Jedi Battle Meditation during his day. As a result, Master Rancisis acted as commander of a number of conflicts during his time as a Jedi Master. Decades before the Clone Wars during the Stark Hyperspace War, Master Rancisis helped coordinate the Republic's forces on Troiken as they battled against Iaco Stark and the Stark Collective.

Years later when the Separatist Crisis threatened to plunge the galaxy into war, Master Rancisis was almost two-hundred years old, an incredibly old age for a Thisspiasin. In the years leading up to the Clone Wars, the Jedi were called to answer the crises that seemed to plague almost every system in the Republic. Master Rancisis was called upon to act as chief negotiator in peace talks between Kashyyyk and Trandosha, home of the Wookies and Trandoshans respectively, two ancient and bitter enemies. Unfortunately, the Jedi Council recalled Master Oppo when the peace talks fell apart and only added to the growing crisis.