摄政是指在君主制下，一个国家的即位君主不能管理国家时，由他人代替君主处理国政。摄政最常见的情况即是君主仍然幼小而不能亲自定夺裁批朝政。在君主患病或不在国内等情况下也会偶尔出现。摄政者多由在位君主的直系亲属担任职务，如储君（称为监国）或母亲，或是通常被称为摄政王的皇族所担任。除此之外，摄政者也有由君主的外祖父等外戚，或是德高望重、深具资历经验的大臣（称为辅政大臣）所担任的。

有些摄政者摄政时，国家并没有君主在位，这种情况下的摄政者是国家的实际统治者，只是没有君主身份。

在摄政期间，摄政者给予建议、并让皇帝从各项建议与运行中进行学习，直至年岁更长，而能亲自执政为止。然而，于很多情况，摄政者都会独揽大权不放，甚至把皇帝当作傀儡。故皇帝长大后，亦往往与这些摄政者产生权力矛盾，而引发权力斗争。单以清朝为例，就有清初康熙帝除去鳌拜，清末光绪帝尝试与慈禧太后争权（但失败）等例子。

A regent (from the Latin regens, "[one] ruling") is "a person appointed to administer a state because the monarch is a minor, is absent or is incapacitated." The rule of a regent or regents is called a regency. A regent or regency council may be formed ad hoc or in accordance with a constitutional rule. "Regent" is sometimes a formal title. If the regent is holding his position due to his position in the line of succession, the compound term prince regent is often used; if the regent of a minor is his mother, she is often referred to as "queen regent".