在罗马天主教会内，对立教宗，或称敌对教皇、伪教宗、反教皇，指由具争议的教宗选擧而得到可以成为教宗的名誉之人。由于天主教枢机团自欧洲中世纪开始负责选擧教宗，这些对立教宗通常与已被枢机团选出的人对立。一些来自较少的教会而自称教宗之领导也可以称为对立教宗。

罗马天主教的动荡时期中进行了具争议的选擧。其中一些如费利克斯五世的选擧被大部分教宗选擧人士认为无效。另外，一些如对立教宗克勉七世的选擧在选后被宣布无效。

最早的对立教宗Hippolytus由公元3世纪的一批教会分裂人士在罗马城选出来对抗教宗卡利克斯特一世。Hippolytus在卡利克斯特一世的承继人庞提安陪同下被流放到萨丁岛的矿场。后来Hippolytus在死前与天主教会和解，并在死后被教会封为圣人。11世纪和12世纪，神圣罗马皇帝和诸教宗争持导致最多对立教宗的出现。一方面，众皇帝经常支持对立教宗来加强自身本钱；另一方面，诸教宗亦会支持身在德国，反抗众皇帝而宣称拥有帝位的人来左右帝国政策。

An antipope (Latin:antipapa) is a person who, in opposition to the one who is generally seen as the legitimately elected Pope, makes a significantly accepted competing claim to be the Pope, the Bishop of Rome and leader of the Catholic Church. At times between the 3rd and mid-15th century, antipopes were supported by a fairly significant faction of religious cardinals and secular monarchs and kingdoms. Persons who claim to be pope, but have few followers, such as the modern sedevacantist antipopes, are not classified with the historical antipopes.