They

In or about the start of the 13th century, they was imported from a Scandinavian source (Old Norse þeir, Old Danish, Old Swedish þer, þair), in which it was a masculine plural demonstrative pronoun.

At the same period (and indeed before), Scots texts, such as Barbour's Bruce, have the th- form in all cases.The development in Middle English is shown in the following table.

[9][10][11] However, the online edition of the Oxford English Dictionary records usage of they "referring to an individual generically or indefinitely", with examples dating to 2008–2009.

[14] The pronoun they can also be used to refer to an unspecified group of people, as in "In Japan they drive on the left", or "They're putting in a new restaurant across the street."

It often refers to the authorities, or to some perceived powerful group, sometimes sinister: "They don't want the public to know the whole truth."