Knot Beret

Knot Beret (ノットベレー) is a enemy from Mega Man X4. There is a modified version of it in Mega Man X5 called Shitappers. They are the short, fat enemies that are the basic soldiers of Repliforce that appear in certain stages. 

Knot Beret B
Knot Beret B throws bombs. 

Knot Beret G
Knot Beret G uses a gun. 

Knot Beret S
Knot Beret S is a snowboarder Knot Beret that appears in Frost Walrus' stage. 

Shitappers
Shitappers (シタッパーズ) are enemies similar to the Knot Berets that appears in The Skiver's stage. 

Trivia

 * Shitappers is the same Japanese name of the Birdbots from the Mega Man Legends series, which can be translated as "underling".