Iambic pentameter () is a type of metric line used in traditional English poetry and verse drama. The term describes the rhythm, or meter, established by the words in that line; rhythm is measured in small groups of syllables called "feet". "Iambic" refers to the type of foot used, here the iamb, which in English indicates an unstressed syllable followed by a stressed syllable (as in a-bove). "Pentameter" indicates a line of five "feet".

Iambic pentameter is the most common meter in English poetry. It was first introduced into English by Chaucer in 14th century on the basis of French and Italian models. It is used in several major English poetic forms, including blank verse, the heroic couplet, and some of the traditionally rhymed stanza forms. William Shakespeare famously used iambic pentameter in his plays and sonnets, John Milton in his Paradise Lost, and William Wordsworth in The Prelude.

As lines in iambic pentameter usually contain ten syllables, it is considered a form of decasyllabic verse.