An unofficial member was a member of a colonial legislative council

Legislative Council

A Legislative Council is the name given to the legislatures, or one of the chambers of the legislature of many nations and colonies.A Member of the Legislative Council is commonly referred to as an MLC.- Unicameral legislatures :...

 or an executive council

Executive Council (Commonwealth countries)

An Executive Council in Commonwealth constitutional practice based on the Westminster system is a constitutional organ which exercises executive power and advises the governor or governor-general. Executive Councils often make decisions via Orders in Council.Executive Councillors are informally...

, appointed by a governor

Governor

A governor is a governing official, usually the executive of a non-sovereign level of government, ranking under the head of state...

 to sit in the council(s) alongside with ex officio members. A senior unofficial member would be appointed by the governor from among the unofficial members. Unofficial members might also be appointed to unelected or partially-elected municipal and district councils, where there were ex-officio members.

Currently the Executive Council of Hong Kong is still composed of ex officio members (official members since 1997) and unofficial members (non-official members since 1997). One of the non-official members is appointed by the Chief Executive (until 1997 the Governor) as the convenor (until 1994 the senior unofficial member).