The first character of Diablo IV is excluded, but this is not a class. Lilith, the daughter of Hated, will return for Diablo IV .
A new book of works by Diablo spoils some Diablo IV details before the official Blizzcon 2019 game reveals. Thanks to the book, we know that Lilith, the queen of Sukubi, the mother of all nephalim, and the daughter of Prime Minister Evil Mephisto (also known as the Lord of Hate, known as the good boss of the MF), will be the demonic boss in the new game.
There is no actual screenshot of how Lilith will appear in Diablo IV, just some concept art. We also don't know what new classes will be included or whether old classes like Amazon, Druid or Paladin will return to Diablo IV. I'm also curious to know which Prime Evils will appear, but discussing this lengthwise will, of course, spoil Diablo III.
The last time we saw Lilith during a game was in Diablo II: Lord of Destruction as one of the uber mini bosses. I remember beating her many times in the pursuit of that perfect Paladin Torch.
What we know about Diablo IV so far:
- There will be dark, dark horror themes and tuning, no cartoon visuals
- Reveal set for Blizzcon 2019
- Traditional isometric action RPG
- Wants to be "Modern Diablo II"
- Some kind of monetization, but not a real money auction house
- Probably comes to computer first
- Possible cross game with consoles and computer  Developed for years, first jobs popped up in 2016
- Diablo IV was restarted once, initially started as a third party action game
- the ongoing iteration is demonstrated for employees, Blizzard is very enthusiastic about it