Phalangite

A phalangite was a Macedonian soldier who fought in the Macedonian phalanx formation. The phalangites evolved from the hoplites but had much lighter equipment.

Unlike the hoplites, a phalangite was a semi-professional soldier. They were drawn from the upper peasant class, who owned property and voted but were not quite nobles, and could afford to practice several hours every day. They usually provided their own armor and shields, since they could afford them; they did not need to be equipped by their superiors. Their usual equipment was the linothorax (hard, layered, leather body armor), the 6+ meter sarissa, and a short sword for close-combat defense.

The phalangite was similar to the classical hoplites in many ways; though they differed in armor, they had many of the same motivations. Both fought alongside friends, neighbors, and countrymen for the good of the (city-state, kingdom, etc.) that they belonged to, and had much invested in the outcome of the battle (even if they survived); the same was not true for a mercenary. This made both disciplined, loyal, and highly motivated soldiers who served well in their respective armies.

Tactics
The phalangites could be used as an offensive tool, but their purpose was mostly to hold the enemy in place while the light infantry and heavy cavalry attacked the enemy flanks. The phalangites were the center of hellenistic armies and were deployed with 256 men in one formation called a "syntagma", which was 16 men deep. As such phalangites hardly made up the majority of macedonian armies, as often depicted in popular culture. For instance, Alexander the Great invaded Asia Minor with (roughly) 31,000 men of which only 9,000 were phalangites. The rest were either hoplites, peltasts or other infantry. An army made up of only phalangites was not very efficent since their flanks were vulnerable too attack.

Phalangites, being trained professionals, also carried their own supplies which drastically reduced the size of the supply trains and allowing macedonian armies to march much faster than greek or persian contemporaries.

Phalangites replaced the hoplite as the standard infantryman for greek armies. Even other non-hellenistic factions adopted the macedonian phalanx, such as Carthage and Pontus.

Decline
Eventually the tactics of the phalangites changed and the phalanx itself became the offensive arm of the hellenistic kingdoms. They were still deadly formations, but a phalanx needed support for it to be truly succesfull. The romans had great trouble fighting phalanxes but overcame them due to the fact that later hellenistic generals neglected the need for offensive and mobile elements in their army, such as light infantry and heavy cavalry.