First appearance: The Avengers #112, June 1973. She was the daughter of a Vietnamese mother, Lua Khrul, and a German father, Gustav Brandt (Libra), who later became a terrorist, and was revealed to be the Celestial Madonna in Steve Englehart’s notable storyline from 1974-75. Her exact first name does indeed appear to be Mantis.* She later took up the pseudonym of Mandy Celestine when living in Connecticut.
Current status: not certain.
Was subjected to the following acts of discrimination: she had to give up custody of her child to her father’s people, and during her adventure in space with the Silver Surfer, she was struck by an explosion that caused her to literally split into multiple versions of herself, an effect that apparently had what to do with the powers she was developing, and she had to find all the pieces in order to set things – and her memories – right again. In 1995’s disastrous story, “The Crossing” she returned as the villainous bride of Kang the Conqueror, plagued with a lot of hatred towards the Avengers for telling her manipulative lies. This was later retconned by Kurt Busiek in 1998, when he wrote a story where it was revealed that it was actually a Space Phantom brainwashed into thinking he was Mantis.
What’s wrong with how this was done? “The Crossing” was one of the most awful ideas in the history of the Avengers that almost ruined a good character. That she had to abandon her child was probably also ill-advised, though he was still around, and later turned up again.
Was there anything good to come out of this? Kurt Busiek had a good idea to retcon the damage done in 1995, and in Avengers: Celestial Quest, Steve Englehart took up writing an Avengers story again in which he wrote that Mantis remerged with the remaining fragments of her personality that she’d split into, regaining a lot of her lost memory sections. During this miniseries, she and the Avengers traveled into space to find her son and save him from a clone of Thanos who was targeting him. It’s good that she got to reunite with her child in the end!
* Thanks to Kurt Busiek for providing some details on this.