Kellner is a surname and may refer to:
- Alex Kellner (1924–1996), baseball pitcher
- Carl Kellner (optician) (1829–1855), German optician
- Carl Kellner (mystic) (1851–1905), Austrian mystic, founder of Ordo Templi Orientis
- Catherine Kellner
- Dan Kellner (born 1976), American fencer and graphic designer
- Donald Ferdinand Kellner
- Douglas Kellner
- Esther Kellner
- Friedrich Kellner (1885–1970), Justice Inspector and Nazi opponent
- Gyula Kellner, Hungarian athlete
- Jamie Kellner
- Johann Christoph Kellner, German composer, son of Johann Peter Kellner
- Johann Peter Kellner, German composer, father of Johann Christoph Kellner
- Leon Kellner (de)
- Lorenz Kellner, German educator
- Larry Kellner
- Micah Kellner
- Oscar Kellner (1851–1911), German agronomist
- Paul Kellner
- Peter Kellner (born 1946), British journalist
- Petr Kellner
- Rosa Kellner
- Uwe Kellner
- Walt Kellner
- William Kellner