Something with two legs that guards is commonly called a "guard" or "sentinel." This could refer to a human security guard or even a fictional creature in stories or games. In a broader sense, it could also describe animals like certain birds that protect their nests. The term ultimately depends on the context in which it's used.
Sentry (GateKeeper)
Something that walks on two legs is called a biped and something that walks on four legs is a quadruped.
It's from something called "Composition on a Pig."
Dinosaurs that walk on two legs are called "bipeds". The term applies to all animals that walk on two legs.
Creatures that walks on two legs are called bipeds.
The legs.
Legs
Leggiches
Basketball is played with 5 men on each side. Usually there are 2 guards, 2 forwards, and one center. The two guards are called the point guard (called the 1) and the shooting guard (called the 2). The two forwards are called the small forward (called the 3) and the power forward (called the 4). The center is known as the 5.
An animal with legs might be called a biped or a quadruped. An animal without legs can move in a two-anchor movement or in a lateral undulation movement.
the legs
The are called bipeds. Bi= 2. peds= feet