As a type of irregularity and anomaly, suppletion has been widely investigated in Indo-European languages. It is generally thought that Turkic languages, as they are very agglutinating, do not tolerate such irregularities. Though this is true to a certain extent, suppletion may be observed in any natural language as a universal linguistic phenomenon. Turkic languages contain a considerable number of radical and affixal suppletive pairs. In this article I deal with those suppletive pairs in historical and contemporary Turkic languages and comment on their rise and degradation through phonological and semantic shifts, language contact or analogy. I will revisit and reorganize certain pairs which have been falsely classified as suppletive. Since it is important to distinguish suppletive pairs from separate lexical and grammatical morphemes, I will also clarify some theoretical points regarding apophony, uniqueness, the productiveness of single paradigms, lexicalization, synonymy and antonymy.