Portrayed as a mad scientist, Dr. Finkelstein performs experiments in his laboratory, mainly trying to create life. He created Sally, a living doll who became his assistant. Confined to a wheelchair, Finkelstein has trouble getting around. He wears a helmet which can access his brain which he scratches thoughtfully at times. He can be grouchy at times, and is initially too busy in his experiments to develop friendships—although Jack Skellington seems to have succeeded. At times he can be kind, but this is rarely seen. He reprises a minor role in Kingdom Hearts 358/2 Days, alongside Jack and Zero.
The doctor is an extremely irritable, grouchy old man. He has great passion for inventing in his lab, though showing no skill at inventing whatsoever, shown by the following things: Sally was obviously not supposed to be a "good for nothing girl," and the artificial heart, the memory-recovery potion, and the experiment all turned out wrong.
Dr. Finkelstein is a frail-looking person, with thin, spindly limbs and very small hands and feet, but a disproportionately large head. He is confined to a black, electric wheelchair that seems to be rather old and difficult to operate. The chair is almost entirely metal and lacks any sort of cushioning, and it sports two levers, one on either arm rest, that Finkelstein uses to move it.
Finkelstein himself dresses in a white lab coat that buttons up on the right side, pants of the same color, black shoes, and black gloves that are a good deal wider than his arms. His skin is an unhealthy white color and he has small, beady black eyes, normally covered by his goggles, as well as thin black eyebrows. His mouth is beak-like in structure and he seems to be missing a few teeth. Finkelstein's ears and nose are so small as to be almost nonexistent, and his nostrils point forward.
Easily, Dr. Finkelstein's most prominent feature in his skull, which bears several obvious bolts and a clear horizontal seam going around the middle. Finkelstein can literally flip his skull open via a hinge in the back, exposing his pink brain, which he often scratches when attempting to figure something out.
In this game, he creates a guidance system to control the Heartless's movements for their festival that year. But when the doctor tries adding a heart to the guidance system, it causes a complete backfire, reverting the Heartless to their destructive natures and try attacking the residents of Halloween Town.
After "improving" his artificial heart with more emotions, the doctor has his work stolen from him by Lock, Shock and Barrel, who give it to Oogie. In the aftermath of Oogie's plot, the doctor gives up on trying to make a heart as he finds it almost impossible to comprehend.
As a figment of Sora's memories, Doctor Finkelstein makes an appearance in the recreation of Halloween Town. This time, the doctor has grown concerned about memories not reflecting the truth, and has crafted a potion out of forget-me-nots to bring out the truth of the memories that lay deep in hearts. However, once he sniffed it, Heartless began appearing in droves, which led him to believe his potion works.
However, if someone actually drank it, the figment of Sally had stolen his potion out of fear something worse than Heartless might appear. The figment of Oogie, however, stole his potion from Sally and swallowed almost all of it, causing him out fear immense fear out of the memories of what happened o the actual Oogie Boogie. Dr Finkelstein gave up on his potion after gathering his data on the effects i had on himself and Oogie after Sora declined to drink what remained of the rest of it.
Dr. Finkelstein appears once again in Kingdom Hearts 358/2 Days, helping Jack with his new ideas for Halloween. He is seen in the Town Square with the Pumpkin King on Roxas's second visit to Halloween Town, examining Jack's Heartless-filled balloons.
Dr. Finkelstein makes his return in this game as well. He is busy constructing a robotic creature with the help of Lock, Shock, and Barrel to be their friend, but their mischievous ways are annoying him. He finishes his experiment before Sora's return trip to Halloween Town, but the experiment escapes after attacking the doctor, and is dismantled in a battle against Sora and his friends in Christmas Town. Dr Finkelstein concludes that it escaped to search for the heart it did not have.
In Tim Burton's classic film, Dr. Finkelstein is the same character portrayed in the Kingdom Hearts series. As the creator of Sally, the doctor is exasperated and extremely irritated as Sally spikes his food and puts him to sleep while she ventures out. He usually tracks her down and returns her to the laboratory, locking her in her room.
After Jack returns from Christmas Town, Dr. Finkelstein give him the tools to perform some experiments to explain the meaning of Christmas. When Jack decides to run Christmas, he asks Dr. Finkelstein to create reindeer for a sleigh. He does, however, creating skeletal versions of it. Finkelstein spends the remainder of the film building a new assistant, who becomes a female version of him.
- While Kingdom Hearts II serves as the Doctor's name's first mention in a voiced cutscene, it is mispronounced, Jack calling him "Finkel-steen" rather than the film's version of the name, "Finkel-stine."