Here is the full list of all 25 Diablo IV achievements.
Imprint 10 items at the Occultist with an Aspect from the Codex of Power.
Upgrade your Healing Potion to max tier.
Acquire 10 Caches of Chaos from the Tree of Whispers.
Explore all of Estuar.
Craft any Elixir and any Incense.
Complete a Sacred and Ancestral Nightmare Dungeon.
Upgrade a piece of Armor, Jewelry, and a Weapon.
Collect 1000 Aberrant Cinder in Helltide zones.
Kill any World Boss.
Complete the campaign.
Reach Level 50 with any character.
Kill 666 Snakes or Spiders.
Kill 666 Bandits, Cultists, or Knights.
Kill 666 Drowned, Vampires, or Werewolves.
Kill 666 Ghosts, Skeletons, or Zombies.
Kill 666 Demons, Fallen, or Goatmen.
Kill 100 enemies with Fire, Frost, or Lightning damage as a Sorcerer.
Kill 50 enemies while Berserking as a Barbarian.
Kill 50 enemies in Werebear form and 50 enemies in Werewolf form as a Druid.
Reach Level 50 with a Hardcore character.
Reach Level 100 with any character.
Summon 100 Skeleton Mages or Warriors as a Necromancer.
Get 5 PvP kills.
Kill 50 enemies in melee range and 50 enemies out of melee range as a Rogue.
Kill the most challenging Echo of Lilith.