威廉·理乍得·瓦格纳（德语：Wilhelm Richard Wagner，1813年5月22日－1883年2月13日），德国作曲家，以其歌剧闻名。理乍得·瓦格纳不同于其他的歌剧作者，他不但作曲，还自己编写歌剧剧本。他是德国歌剧史上一位举足轻重的人物。前面承接莫扎特、贝多芬的歌剧传统，后面开启了后浪漫主义歌剧作曲潮流，理乍得·施特劳斯紧随其后。同时，因为他在政治、宗教方面思想的复杂性，成为欧洲音乐史上最具争议的人物。

理乍得·瓦格纳一开始是延续卡尔·马利亚·冯·韦伯和贾科莫·梅耶贝尔的浪漫主义传统，但后来提出了整体艺术的概念，集成了诗歌、视觉艺术、歌剧及剧场，并在1849至1852年间提出许多的论述。瓦格纳后来将这些概念放入由四部歌剧组成的系列歌剧《尼伯龙根的指环》中，共花了26年的时间才完成。

Wilhelm Richard Wagner (/ˈvɑːɡnər/; German:[ˈʁiçaʁt ˈvaːɡnɐ]; 22 May 1813 –13 February 1883) was a German composer, theatre director, polemicist, and conductor who is primarily known for his operas (or, as some of his later works were later known, "music dramas"). Unlike most opera composers, Wagner wrote both the libretto and the music for each of his stage works. Initially establishing his reputation as a composer of works in the romantic vein of Weber and Meyerbeer, Wagner revolutionised opera through his concept of the Gesamtkunstwerk ("total work of art"), by which he sought to synthesise the poetic, visual, musical and dramatic arts, with music subsidiary to drama. He described this vision in a series of essays published between 1849 and 1852. Wagner realised these ideas most fully in the first half of the four-opera cycle Der Ring des Nibelungen (The Ring of the Nibelung).