Warning: SPOILERS for Midnight Mass.
One of the most peculiar characters in Midnight Mass is Mildred Gunning, and she's played by actress Alex Essoe. Midnight Mass is the latest Netflix series from horror mastermind Mike Flanagan, who captivated audiences with his many horror movies, like Gerald's Game and Doctor Sleep, but particularly with the shows The Haunting of Hill House in 2018 and The Haunting of Bly Manor in 2020. Now, while Midnight Mass steps away from the haunted house formula and travels to an isolated island, it's still no less intriguing.
Fundamentally, Midnight Mass explores Christianity, the concept of angels, and how biblical canon can apply to the modern day. Much of it is told through characters like Father Paul/Monsignor Pruitt (Hamish Linklater), Riley Flynn (Zach Gilford), and Erin Greene (Kate Siegel), but one of many characters stands in the middle of it all, Mildred Gunning. She's the elderly mother of Dr. Sarah Gunning, who spends her free time taking care of her mother who seems to suffer from dementia as well as a broken hip. However, despite incredible makeup work, Mildred doesn't really look like an 80+ year-old.
Mildred Gunning is played by Alex Essoe, who's in her late 20s and a far cry from being a retiree - and the reason Essoe portrays Mildred becomes clear as Midnight Mass' story develops. This series marks the third time that Essoe has collaborated with Flanagan, having previously portrayed Wendy Torrance in Doctor Sleep (taking over for Shelley Duvall who first played the character in The Shining) and Charlotte Wingrave in 2020's The Haunting of Bly Manor.
Aside from her appearances in Flanagan's movies and shows, Essoe has also starred in projects such as Passion Play and Ecstasy in the early 2010s, ultimately landing her first major role as Sarah Walker in 2014's Starry Eyes. Then in 2015, she played Lynn in the "Grim Grinning Ghost" segment of Tales of Halloween. Over the next few years, she landed prominent parts in Midnighters, The Super, and Death of Me, among other projects. But after appearing in Doctor Sleep in 2019, it's safe to say she'll now be one of Flanagan's frequent collaborators going forward.
Interestingly, even knowing Alex Essoe plays Mildred Gunning in Midnight Mass, she's virtually unrecognizable for most of the series, only appearing as her true self in the final episode. But it becomes obvious throughout the series that she's been aged through makeup (and potentially prosthetics) - lots of it, and for good reason.