Placekicker

Placekicker, or simply kicker (PK or K), is the player in American and Canadian football who is responsible for the kicking duties of field goals and extra points. In many cases, the placekicker also serves as the team's kickoff specialist or punter as well.

The kicker initially was not a specialized role. Prior to the 1934 standardization of the prolate spheroid shape of the ball, drop kicking was the prevalent method of kicking field goals and conversions, but even after its replacement by place kicking, until the 1960s the kicker almost always doubled at another position on the roster. George Blanda, Frank Gifford and Paul Hornung are prominent examples of players who were stars at other positions as well as being known for their kicking abilities. When the one-platoon system was abolished in the 1940s, the era of "two-way" players gave way to increased specialization, teams would employ a specialist at the punter or kicker position. Ben Agajanian, who started his professional career in 1945, was the first confirmed place-kicking specialist in the NFL, kicking for ten teams. (There is some evidence that Ken Strong and Phil Martinovich, both in 1939, and Mose Kelsch, in 1933 and 1934, may have preceded Agajanian as players who spent their seasons doing nothing but kicking.)

Because of the difference in techniques needed, to avoid leg fatigue, and to reduce the risk of injury, on the professional level most teams employ separate players to handle the jobs. The placekicker usually will only punt when the punter is injured, and vice versa. (One player often handles both jobs in the Canadian Football League, which has smaller active rosters than in the NFL.) A professional team will occasionally even have a "kickoff specialist" who handles only the kickoffs and serves as a backup to the kicker who handles field goals and extra points. This is typically done to further protect a premier point-scoring kicker from injury or if he, while accurate, does not have sufficient distance on kickoffs.

...
Wikipedia