The group of elements that satisfies the octet rule without forming compounds is the noble gases, located in Group 18 of the periodic table. These elements include helium, neon, argon, krypton, xenon, and radon.
Noble gases are unique because they have a complete outer electron shell, which means they possess eight electrons (except for helium, which has two) in their valence shell. This complete octet renders them very stable, and as a result, they have little tendency to gain, lose, or share electrons. Consequently, noble gases do not readily form chemical bonds with other elements, which means they typically exist in nature as monatomic gases.
In essence, their inherent stability due to having a full valence shell makes them highly unreactive, allowing them to satisfy the octet rule without the need to engage in compound formation.