A person empowered by a shareholder to vote on his behalf at company meetings such as the annual general meeting (AGM) and extra-ordinary general meeting (EGM).
Shareholders who cannot attend meetings will fill in proxy cards stating which way they wish to vote and the meeting.
This is a fairly straightforward affair in the UK in that all shares are registered either in the name of the beneficial owner or in the name of a nominee company which knows who the beneficial owner is.