This is Mad Madam Mim, a giant devil's flower mantis (Idolomantis diabolica). They are native to a few countries in Africa and can grow up to five inches long. Raising one in captivity requires a special environment and lots of attention, as Madam Mim’s owner, redditor ImSweeches, will tell you. They will only eat flying insects, and require a controlled temperature and humidity. They live about a year with proper care. These mantids are not for beginners.
They are a HIGHLY sought after species and are generally sold out unfortunately. It took me over a year of frequent checking to find them in stock.
EDIT!!!*** PLEASE PLEASE KNOW THIS IS AN INCREDIBLY SENSITIVE SPECIES! Even experienced hobbyists have difficulties raising this variety. The attention this is getting has my gut sinking thinking about people who have never cared for a mantis buying these up and killing them because they're not ready
There are several great beginner mantids: Giant African mantis (sphoromantis viridis) ghost mantis (phylocrania paradoxa) and giant Asian mantis (hierodula patellifera) are just a few great species to start with.
See more pictures of Mad Madam Mim and other insects at sweeches’ Instagram page.