A Null Object is an object that extends a base type with a null or neutral behavior. Here’s the Scala version of the Java example Wikipedia uses to demonstrate this:

trait Animal {
  def makeSound()
}

class Dog extends Animal {
  def makeSound() { println("woof") }
}

class NullAnimal extends Animal {
  def makeSound() {}
}

As you can imagine, later in your application you might have some code like this: