天使投资者（英语：Angel investor）或天使，在欧洲称为商业天使（Business Angel）或非正式投资者，是指提供创业资金以换取可转换债券或所有权权益的富裕个人投资者。天使投资人自己组织成的天使团体或天使网络目前正不断扩大，以分享研究成果和集中资金针对性。术语“天使”最初来自英格兰，代表提供戏剧表演资金的资本。1978年，新罕布什尔大学教授、该校创业研究中心的创始人William Wetzel完成了一项开拓性研究：探讨在美国如何增加企业的原始资本，他第一次使用“天使”来描述那些支持这些企业的投资者。

An angel investor or angel (also known as a business angel, informal investor, angel funder, private investor, or seed investor) is an affluent individual who provides capital for a business start-up, usually in exchange for convertible debt or ownership equity. A small but increasing number of angel investors invest online through equity crowdfunding or organize themselves into angel groups or angel networks to share research and pool their investment capital, as well as to provide advice to their portfolio companies.