法院之友（拉丁语：Amicus curiae，或amicus curiæ，复数形为amici curiae），也译为法庭之友，法律名词，最初源自于罗马法，后被英美习惯法所继承。

法院之友不是诉讼当事人的任何一方；可能是出于自愿之下，或是回应诉讼双方的当事人请求，法院之友提出相关信息与法律解释的法律文书给法庭，以协助诉讼进行，或让法官更了解争议的所在。提出这种法律文书的人，就被称为法院之友。法庭之友提交给法庭的文书是影响法庭裁判的重要工具。他可以支持诉讼的任一方，也可以单独主张自己的观点。法庭之友可以就案件的裁判请求法庭做出特别的行动，也可以仅仅就某项法律或进程阐述观点。总之，法庭之友通过搭乘诉讼案件的便车，向法庭陈述观点，以期达成影响案件判决、解释法律、甚至是推动公共政策、影响政治过程的目的。

An amicus curiae (literally, friend of the court; plural, amici curiae) is someone who is not a party to a case and offers information that bears on the case, but who has not been solicited by any of the parties to assist a court. This may take the form of legal opinion, testimony or learned treatise (the amicus brief) and is a way to introduce concerns ensuring that the possibly broad legal effects of a court decision will not depend solely on the parties directly involved in the case. The decision on whether to admit the information lies at the discretion of the court. The phrase amicus curiae is legal Latin.