|Appearance||Tales of the Abyss|
|Japanese Voice Actor||Mariko Suzuki|
Professor Gelda Nebilim
Gelda Nebilim was born in N.D. 1966. She once led part of the Oracle Knights in the Order of Lorelei, serving as Locrian Colonel during her tenure. Under orders from Fon Master Evenos, she runs several special investigations into relics known as the Catalyst Weapons, six weapons that shared the power of Rem and Shadow, the aggregate sentiences of Light and Darkness. At one point during these investigations, Nebilim fails a planetary arte experiment administered at Mt. Roneal, resulting in the death of many Oracle Knights in N.D. 1991. After the accident, she leaves the Oracle Knights and opens a private school in the Keterburg. Unlike any teacher before her, Professor Nebilim shares an important bond with her students, treating them as children she never had. Upon the arrival of a young Jade, Nebilim senses the boy's twisted mind, lacking no ability to distinguish the guilt or the pleasure in taking a life for achieving his ends. Realizing this, she seeks to change his heart, leading him to develop his fomicry methods to form a better cause.
Along with Jade, Nebilim also taught a boy named Saphir Ortion Gneiss, who later becomes obsessed with reviving her, even joining the God-Generals under the assumed name of Dist to aid in doing so. She helps conceal knowledge of the young Peony Upala Malkuth IX, having escaped from his isolated mansion to join the school and learn like the other kids, as she understands the importance of an emperor understanding his people. One night, Jade attempts a fonic arte using the Seventh Fonon, causing the fonons to go out of control due to his inability to control them. The resulting explosion leads to a near fatal injury sustained by Nebilim in an attempt to protect the children in her care. Jade, accompanied by Saphir, takes the wounded professor to the outskirts of town, where he decides to use fomicry to save her life.
The result ends in catastrophe. As the research in fomicry during the time relied entirely on the knowledge of two children, the replication process remained largely untested and theoretical. In an attempt to replicate their professor, Jade creates an unstable replica, a mere facsimile of the original Nebilim, with a never-ending hunger for the first and sixth fonons since the process rendered the replica weak due to the imbalance of fonons that compose her body. The replica Nebilim engages in a killing spree by taking the life of several fonists in the region in order to devour the fonons she requires to gain stability. Following these events, the Malkuth Empire declares a state of emergency in which its army, at the command of field Marshal McGovern, confronts the replica Nebilim. Eventually, Malkuth's fonists manage to seal her in a hidden cavern that is later known as Nebilim's Crag, an isolated cave in the center of Mt. Roneal's merciless terrain.
Many years later, Dist attempts to complete his plan to resurrect the professor, which involves the use of the "Planetary Arte Catalysts" that Nebilim had researched while she was still alive. As the task of collecting all six of the Catalyst Weapons would be too difficult alone, Dist orchestrates a plan in which the group, led by Luke fon Fabre, would search for them instead so that they would be collected together and display their full powers.
Upon gathering all six Catalysts, the group travels to Nebilim's Crag. Dist makes an appearance, setting the final stage of his plan into motion by goading the party to place their weapons into a fonic glyph. This act causes a nearby wall to split open and release the replica of the professor who had been trapped within the seal. With these weapons, she is now able to sustain herself with the aid of the six catalysts, two of which give her an infinite supply of the fonons she requires to survive. Once the party defeats her in battle, she attempts to heal herself using the glyph, but Jade reacts quickly and uses the glyph's power against her. He manages to obliterate her using an incomplete power of the "Planetary Fonic Arte". With the replica gone, a weight is lifted from Jade's conscience, knowing that Gelda Nebilim's memory can now rest in peace.
The replica of Gelda Nebilim lives up to her reputation as a very powerful enemy. She possesses impressive offensive and defensive capabilities, and is difficult to stagger, making her even more dangerous when she is casting her fonic artes. She utilizes many various strike and fonic artes derived from the abilities of all party members, and she can use certain normally elementally charged arcane artes without the use of an FOF Circle. Nebilim is also able to execute some of other character's mystic artes, such as Asch's Rending Saber, Arietta's Big Bang, Tear Grants' Innocent Shine and Fortune's Arc, and Jade's Mystic Cage and Indignation. She also possess her own, signature mystic arte, Fragmented End, as well as the fonic arte, Time Stop.
- Nebilim has unused cut-in artwork for Fortune's Arc, depicted in a vertical style.
- While Nebilim was working as a member of the Oracle Knights, she was nicknamed the "Demonic Commander".
- Nebilim's replica uses the "Nebilim" sword in one hand and "Heart of Chaos" rod in the other.
- In Tales of Vesperia, there is a bow named "Nebilim".