Ravager

Illager beasts are large hostile mobs that spawn in raids.

Raids
Illager beasts can spawn as part of raids or illager patrols.

Woodland mansions
Illager beasts can spawn in woodland mansions.

Behavior
Illager beasts are hostile towards players, iron golems, and villagers within a 16-block radius. They attack by ramming enemies with their head, dealing damage and high knockback. They will also destroy crops and leaves that they run quickly into, though flowers, saplings, and crops such as melon and pumpkin stems are unaffected.

If blocked by a shield while attacking, no damage occurs and knockback is halved. The illager beast has about a 50% chance to become stunned and unable to move or attack for around 2 seconds. After this period, it will emit a roar that does damage and high knockback (which increases with proximity) to nearby entities. The roar can knock back nearby Illagers.

Even though they are heavy, they can swim. Their apparent weight gives them 50% chance of 100% knockback resistance. Illager beasts match up to be slightly weaker than iron golems.

Drops
Upon death, illager beasts drop 0–1 s.

Trivia

 * Due to the large amount of health and strength that the illager beast has, it can be considered as a mini-boss, although this has not been stated by Mojang.