When lines of iambic pentameter rhyme in multiple couplets -- that is, in successive sets of two -- they are called “heroic couplets." They gained particular popularity in the 18th century, but they were pioneered by Geoffrey Chaucer in the late 14th century. Chaucer's heroic couplets are also known as "riding rhyme." When lines of iambic pentameter have a more complex rhyme scheme, they can be part of various poetic forms. But you might also encounter a few rhymed lines of iambic pentameter within a poem that mostly uses another meter -- these poems are called “mixed meter.”
Fourteen lines of iambic pentameter that rhyme ABAB CDCD EFEF GG are called a Shakespearean sonnet. Note that this form ends with a couplet, but it’s not called a heroic couplet because it’s the only set of two in the poem. Petrarchan and Spenserian sonnets also use rhymed iambic pentameter in slightly different rhyme schemes. Lines of iambic pentameter in successive quatrains -- four-line stanzas -- that each rhyme ABAB, as in Thomas Gray’s “Elegy Written in a Country Churchyard,” are often called elegiac stanzas. Rhymed iambic pentameter can also occur in lyrical or narrative poetry, especially from the Romantic period; John Keats is particularly noted for this form, and his “Endymion” is an example of a pastoral narrative poem in heroic couplets.