Monstrous Menagerie II: Hordes & Heroes has a launch date! Mark your calendars for November 12th, 2024. 300+ more monsters for your D&D 2024, or Level Up: Advanced 5th Edition games, plus new horde rules and rules for heroic monsters who level up alongside you--whether they be allies, companions, or foes! Click here to follow on Kickstarter!
It's not technically undead, see the first ravenloft creature book for details. But one thing to keep in mind is that when you read it's mind you might go mad!