Golden Age

Doctor Poison first appeared as the chief of the poison division for a Nazi spy band who had planned to contaminate the United States Army's water with "Reverso", a drug that compels whoever takes it to "do the exact opposite of what they are told". She disguised her sex by wearing a bulky hooded costume and a mask. Doctor Poison's underlings captured Steve Trevor and brought him to their base in America where he was questioned by Doctor Poison. Wonder Woman, disguised as a nurse, aided Steve Trevor but was forced to flee the scene after a lengthy battle. Meanwhile, the Reverso drug was successful in turning thousands of American soldiers against their superiors. Wonder Woman recruited Etta Candy to help her create a diversion for Doctor Poison's troops, which led to the defeat of the villain. When Wonder Woman pulled her disguise off, she discovered Doctor Poison to be Maru, a Japanese princess. Maru made one more attempt to defeat the amazon, but was tackled by Etta Candy and coerced into giving up the antidote. She was later taken into police custody.^[6]

Later, Princess Maru escaped imprisonment and disguised herself as Mei Sing, a "princess" who worked in a Chinese nightclub. She once again captured Steve Trevor, who couldn't see through her disguise. This led to another encounter with Wonder Woman, whom Maru defeated with an anesthetic gas grenade. Maru had been perfecting a green gas which would clog the carburetors of the US planes. This plan was foiled once again by Wonder Woman.^[7]

Instead of placing Maru back in prison, Wonder Woman sentenced her to Transformation Island, the Amazon penal colony where many female criminals were sent to reform. Although the majority of inmates have reformed with loving submission, Maru and seven other women refused to change their ways. The Saturnian slaver Eviless banded these rebellious super-villains together under the name Villainy Inc. Maru returned to her Doctor Poison disguise and tricked Queen Hippolyta into believing men had invaded Paradise Island. The villains were able to capture Hippolyta's girdle, which they used to defeat Wonder Woman. Doctor Poison then joined Eviless, Blue Snowman, and Cheetah on a boat with the captive Wonder Woman, plotting to imprison the Amazon on Transformation Island for revenge. Wonder Woman attempted to escape by turning over the boat, but the four members of Villainy Inc. defeated her once again. After traveling to Transformation Island, Eviless tortured Wonder Woman until the reformed criminal Irene led a mutiny against Villainy Inc. In the ensuing chaos, Wonder Woman and Hippolyta broke free of their chains and managed to defeat Doctor Poison and her three companions.^[8]

Post-Crisis

After the events of Crisis on Infinite Earths, Doctor Poison was a founding member of Villainy Inc., but the team was created by Queen Clea instead of Eviless. As part of Villainy Inc., Doctor Poison battled Hippolyta, the first Wonder Woman, in the 1940s.^[9] It was later revealed by her granddaughter that she had died after creating the Reverso drug, as she accidentally reversed her own growth patterns and had forgotten the antidote by becoming too young too fast, eventually reverting to a fetus and then nothing.^[10]

Post-Crisis

The grandchild of the original Doctor Poison, this second incarnation appears in league with the demi-goddess Devastation. Doctor Poison's sex remains ambiguous, the only clues being long fingernails and a lipsticked grimace. She also joined the second Villainy Inc. and once again battled Wonder Woman. This incarnation of Doctor Poison confirmed that her grandmother did battle Queen Hippolyta as Wonder Woman during World War II. She also confirms that her grandmother met her own demise through the "Reverso" drug.

Doctor Poison is one of the villains sent to retrieve the Get Out of Hell free card from the Secret Six.

Doctor Poison was later asked to be a part of the Secret Society of Super Villains, which she accepted. Joining the other scientists on the team, she was assigned to collect soil samples from Logor Jasenovac, Croatia. She added her samples with that of other areas on Earth where genocide took place and helped create the new Wonder Woman villain Genocide. Following the Final Crisis, she was with Cheetah's Secret Society of Super Villains.

The New 52

In September 2011, DC Comics rebooted the continuity of its fictional universe and relaunched all 52 of its monthly books in an endeavor called The New 52. Here, Doctor Maru is re-introduced as the Caucasian daughter of a Russian pair of scientists renowned for their knowledge of poisons. American spies had approached her parents as they thought the doctors' expertise could lead to the United States' domination in biological weaponry. When they refused, the Russian government discovered their practices. Her parents were branded terrorists by Russia, and imprisoned near Siberia where they died during interrogations. Doctor Poison blamed the United States for her parents' deaths and planned to take revenge through chemical attacks.^[11]

DC Rebirth

After the events of DC Rebirth, Doctor Poison's history had been altered. In the current continuity, she is Colonel Marina Maru, a Japanese soldier working for the organization called Poison which had been founded by her family.^[12] During Wonder Woman's first few months in the United States, the Amazon discovered a group of men infected with the Maru Virus, a poison that drives its victims to rage-induced murder.^[13] Ten years later, after Wonder Woman had discovered she had been living a lie for several years, Veronica Cale sent Doctor Poison to attack the Amazon.

In the Watchmen sequel Doomsday Clock, Doctor Poison is among the villains who attend an underground meeting held by Riddler that talks about the Superman Theory. Doctor Poison talks about a rumor that the Amazons forcefully took Wonder Woman back to Themyscira.^[14]