PaperMC/paper-api/src/main/java/org/bukkit/LivingEntity.java

package org.bukkit;

/**
 * Represents a living entity, such as a monster or player
 */
public interface LivingEntity extends Entity {
    /**
     * Gets the entitys health from 0-20, where 0 is dead and 20 is full
     *
     * @return Health represented from 0-20
     */
    public int getHealth();

    /**
     * Sets the entitys health from 0-20, where 0 is dead and 20 is full
     *
     * @param health New health represented from 0-20
     */
    public void setHealth(int health);
}