影子内阁（Shadow Cabinet）是指某些行内阁制的民主国家，其在野党为准备上台执政而设的预备内阁班子；往往由下议院中最大的反对党领袖，物色下院中有影响的同党议员，按内阁形式组建而成。这种制度由英国保守党首创，后为一些英联邦国家所采用。

英国是典型的议会民主制的君主立宪制国家，其议会包括上议院和下议院。上院与君主非选举产生，下院由选民选举产生。议会多数党领袖担任英国首相，并由他负责挑选本党人员组成内阁。而最大的在野党随之成为正式的反对党，并组织“影子内阁”。一般来说，“影子内阁”的成员都是议会议员，与其他所有议会议员领取一样的薪水和补助。常出现的称某人为“影子”贸易与工业大臣，实际是指他为在野党负责贸易与工业的议员。

The Shadow Cabinet is a feature of the Westminster system of government. It consists of a senior group of opposition spokespeople who, under the leadership of the Leader of the Opposition, form an alternative cabinet to that of the government, and whose members shadow or mark each individual member of the Cabinet. Members of a shadow cabinet are often but not always appointed to a Cabinet post if and when their party gets into government. It is the Shadow Cabinet's responsibility to criticise the policies and actions of the government, as well as offering an alternative program.