Nemo Mettler (Swiss Standard German: [ˈneːmo ˈmɛtlər]; born 3 August 1999), known mononymously as Nemo, is a Swiss musician and singer-rapper who plays the violin, piano and drums. They were the first openly non-binary act to represent Switzerland in the Eurovision Song Contest, and later won the 2024 contest with the song "The Code". They were the first openly non-binary musician to win the contest, and the third winner representing Switzerland (following the 1956 and 1988 competitions).

Mettler began their interest in music at the age of three, learning to play the violin, piano and drum machine. They studied opera singing from age nine to thirteen. At the age of ten, they joined the Biel children's opera and performed in Mozart's The Magic Flute which was later used as inspiration for "The Code". At thirteen, they performed in the musical I've Never Been to New York. They also began rapping at this age, competing in Swiss contests and performing songs they independently wrote. They found early success in battle rap as a teenager and performed on season three of the Swiss television show Die grössten Schweizer Talente [de], receiving praise from the judges.

In 2015, Mettler released their first EP Clownfisch, under the name Nemo (CH), which peaked at number 95 in the Swiss charts. In 2016, when they were seventeen, Mettler's single "Cypher" went viral. In 2017, they released the EPs Momänt-Kids and Fundbüro under the name Nemo (CH). Fundbüro contained the single "Du", which reached number 4 in Switzerland. "Ke Bock" and "Himalaya" also charted. In the same year they studied solo singing in jazz and pop at Zurich University of the Arts, won the SRF 3 Best Talent prize, and later settled in Berlin to pursue their music career. In 2018, Mettler won four Swiss Music Prizes, including best song of the year for Du and best concert performance of the year.

After staying in Los Angeles in 2020, Mettler decided to switch from singing in Swiss German to English. On the second season of The Masked Singer Switzerland in 2021, they were unmasked as a panda and finished in fifth place. In 2022, they released their EP Whatever Feels Right, this time under the name Nemo. On 29 February 2024, they were announced as the Swiss representative in the Eurovision Song Contest 2024 with the song "The Code", and performed in the second semi-final of the contest, on 9 May. They won the Eurovision final on 11 May with 591 points, becoming the first openly non-binary performer to win the contest; they also finished with the fourth highest amount of points in the final in the competition's history.

Nemo Mettler was born in Biel/Bienne in the canton of Bern. Their father, Markus Mettler, is an entrepreneur and inventor, and mother, Nadja Schnetzler, a journalist. Nemo's sister, Ella, is a photographer. She collaborates with Nemo in the artistic direction of their projects. Nemo's first name means 'no one' in Latin. During a mission for the Swiss Red Cross in El Salvador in 2018, they said "my parents thought that if I was no-one, I could become anyone."

In 2022, Mettler came out as pansexual via an Instagram story, and as of 2024, they have been in a five-year relationship with their girlfriend, who was the first person they came out as non-binary to.

In November 2023, Mettler publicly came out as non-binary in an article in the SonntagsZeitung, after being closeted since around 2021. In the article, Mettler also stated that they prefer to be referred to by their given name, Nemo, instead of pronouns in German, and by they/them pronouns in English.

From 2021 to 2024, Mettler lived in Berlin, then moved to London. Since July 2025, Mettler has been living in Paris.