["person who carries"] late 14c. (mid-13c. as a surname), portour, "person who carries" (goods, burdens), especially one who carries burdens or runs errands for hire, from Anglo-French portour, Old French porteor "porter, bearer; reporter" (12c.), from Late Latin portatorem (nominative portator) "carrier, one who carries," from past participle stem of Latin portare "to carry," from PIE root *per- (2) "to lead, pass over."
["doorkeeper, janitor"] mid-13c. (late 12c. as a surname), "one who has charge of a door or gate; one who guards the gate of a bridge," from Anglo-French portour, Old French portier "gatekeeper" (12c.), from Late Latin portarius "gatekeeper," from Latin porta "city gate, gate; door, entrance," from PIE root *per- (2) "to lead, pass over."
type of dark-brown malty beer, 1734, short for porter's ale (1721), porter-beer, etc., from porter (n.1), said to be so called because the beer was made for or preferred by porters and other laborers, being cheap and strong, and it survived into 20c. largely in Ireland. However, as OED points out, "There is no direct contemporary evidence as to the origin of the name," to which Century Dictionary (1897) adds, "There is no evidence that London porters, as distinguished from London cabmen or London artisans, favored this sort of beer."