A back vowel is any in a class of vowel sound used in spoken languages. The defining characteristic of a back vowel is that the highest point of the tongue is positioned relatively back in the mouth without creating a constriction that would be classified as a consonant. Back vowels are sometimes also called dark vowels because they are perceived as sounding darker than the front vowels.

Near-back vowels are essentially a type of back vowels; no language is known to contrast back and near-back vowels based on backness alone.

The category "back vowel" comprises both raised vowels and retracted vowels.

In their articulation, back vowels do not form a single category, but may be either raised vowels such as [u] or retracted vowels such as [ɑ].

The back vowels that have dedicated symbols in the International Phonetic Alphabet are:

There also are back vowels that do not have dedicated symbols in the IPA:

As here, other back vowels can be transcribed with diacritics of relative articulation applied to letters for neighboring vowels, such as ⟨u̞⟩, ⟨o̝⟩ or ⟨ʊ̠⟩ for a near-close back rounded vowel.

According to PHOIBLE, the most common phonemic back vowel is /u/, occurring in approximately 88% of languages, while the most uncommon phonemic back vowel is /ɒ/, occurring in only 2% of recorded inventories.