乌欧牟 Ulmo，主神语是Ulubôz或Ullubôz。是英国作家约翰·罗纳德·鲁埃尔·托尔金的史诗式奇幻小说《精灵宝钻》中的人物。乌欧牟的意思是「降下大水者」 He who pours，维拉之一，雅睿塔尔之一，他的称号是大海主宰 Lord of the seas、大海之王 King of the Sea、众水之主 Lord of Waters。人类称他为大海之神。

乌欧牟在维拉的权力中排行第三，在曼威和瓦尔妲之后。他没有配偶，性格孤僻古怪，却是曼威最好的好友。他从来不居住在奥玛伦岛或维林诺，除非有什么重大事情争执不下，否则他很少前往维林诺参加维拉们的会议。他居住在外环海 Ekkaia sea中最深渊，名叫乌欧牟那仁 Ulmonan的宫殿中。

Ulmo [ˈulmo] (from the Valarin Ulubôz, Ullubôz via Ulumō) is a fictional character in J. R. R. Tolkien's Middle-earth legendarium. He first appears in The Silmarillion as a god or Vala of the Elven pantheon. Ulmo is a title, which means He who pours. He is also known as King of the Sea and Lord of Waters. Ulmo is similar to the god Poseidon in Greek mythology, Neptune in Roman mythology, Ægir in Norse Mythology, and Manannan in Celtic Mythology. Ulmo was one of the chief architects of Arda (the world).