Ii or ii can refer to:

  • ii (digraph), a digraph in certain romanized alphabets
  • Ii, Finland, a municipality of Finland
  • Ii is a Japanese surname, daimyo of Hikone
    • Ii clan, Japanese clan (Sengoku period)
    • Ii Naomasa, one of four Guardians of the Tokugawa clan
    • Ii Naoyuki, a Japanese author
  • iiNet, a major Australian Internet service provider trading as simply ii;
  • 2 (number), in lowercase Roman numerals
  • Illegal immigrant (especially in Hong Kong vernacular)
  • Invariant chain
  • ii (IRC client), short for IRC It, an Internet Relay Chat client for Unix-like operating systems
  • John Papa Īī, Hawaiian noble
  • Yi language (ISO 639 alpha-2, ii)
  • Supertonic, in music