Epsilon (Ε, ε) is the fifth letter of the Greek alphabet.

Epsilon may also refer to:

• Advance Epsilon, a Swiss paraglider design
• Socata TB 30 Epsilon, a French training aircraft design

• Epsilon, the lowest caste of the World State in the novel Brave New World

• E Channel, also known as Epsilontv, former name of Open TV, a Greek TV channel
• Epsilon, an AI fragment in the web series Red vs. Blue
• Epsilon (イプシロン), an elf girl and the fifth member of Shadow Garden in the light novel and anime series The Eminence in Shadow
• Epsilon (film) (also titled Alien Visitor) (1995) Australian–Italian science fiction film by Rolf de Heer
• Epsilon TV, a Greek regional TV channel

• Epsilon (Blood Stain Child album)
• Epsilon (Dreamtale album)

• Epsilon, an antagonist in the video game Mega Man X: Command Mission
• The Epsilon Program, a fictional religious cult in the video game Grand Theft Auto V

• Error in numerical analysis:
  • Machine epsilon, an error bound in computer arithmetic
  • absolute value of an approximation error
• The epsilon operator introduced by Hilbert
• An infinitesimal value

• EPSILON (programming language)
• Epsilon (text editor)
• Epsilon (rocket), a Japanese solid-fuel satellite launcher
• GM Epsilon platform, an automobile platform
• Hyundai Epsilon engine

• Epsilon (wasp), a genus of wasps
• Hurricane Epsilon (2005)
• Hurricane Epsilon (2020)
• Lancia Epsilon, a car produced by Lancia
• MS Epsilon, a ROPAX ferry
• A subsidiary of marketing company Alliance Data
• SARS-CoV-2 Epsilon variant, a variant of SARS-CoV-2, the virus that causes COVID-19

• Latin epsilon (Ԑ, ԑ), a letter of the Latin alphabet
• Reversed Ze (Ԑ, ԑ), a letter of the Cyrillic alphabet
• All pages with titles beginning with Epsilon
• All pages with titles containing Epsilon