Doctor Gross, outside of her suit, has tan skin and teal colored hair. Due to her extensive modifications, she is extremely mechanized with features including: spider-like legs and the ability to change her body into the weapon of her choice (such as making her arm into 3 rotating saw blades and making her hand into scissor hands). She is also able to send signals through a monocle that activates through winking.
Dr. Gross, sixteen years before her arrival in Ooo and capture of Finn, Jake, and Susan Strong, lived and worked on Hub Island as an instructor and scientist. She worked closely with the Seekers, a group of specialized humans conditioned to keep the island safe and prevent hiders from leaving. At one point, she herself foiled Frieda's escape plan after discovering that she was a hider, using a manipulated Susan Strong (then known by the name of Kara) to destroy her motorized boat and bring her back to "safety" for re-education. Dr. Gross worked closely with Minerva Campbell in order to protect the citizens of Founder's Island.
After Martin Mertens seemingly disappeared from the island after bypassing the Guardian with Minerva's son, Finn, Dr. Gross sent her best seeker, Kara, to find and bring both of them back. While Minerva struggled to cope with the sudden loss and apparent betrayal of her son and husband, Dr. Gross began to conduct strange experiments in her lab, eventually releasing a deadly virus into the population by accident, leading to the deaths of many. After Dr. Gross fled the island, Minerva chose to upload herself into the island's mainframe in order to restore order.
- Her methods for wanting to help upgrade involuntary lifeforms through cybernetics are similar to The Borg Queen from Star Trek, The Next Generation.
- Dr. Gross' suit is reminiscent of the one worn by Dr. Samuel Hayden, from the game DOOM 4, who also was human, but then moved into a cybernetic body.
- Her name and title may be a reference to Heinrich Gross, an Austrian psychiatrist and Nazi war criminal who used the same methods as Dr. Gross.