Müllerian mimicry was discovered and has mainly been researched in insects. However, there is no reason why the mechanisms evolutionary advantages should not be exploited in other groups. There is some evidence that birds in the New Guinea genus Pitohui are Müllerian mimics. Pitohui dichrous and Pitohui kirhocephalus' "share a nearly identical colour pattern" where their geographic ranges overlap, but differ elsewhere; they are conspicuous; and they are chemically defended by a powerful neurotoxic alkaloid, batrachotoxin, in their feathers and skin. This combination of facts implies that the populations in these zones of overlap have converged to share honest warning signals.
Many species of flowers resemble each other but actual mimicry has not been demonstrated. It has been proposed that spiny plants such as Cactaceae and Agave in the Americas, Aloe, Euphorbia, white-thorned Acacia in Africa and spiny Asteraceae of the Mediterranean may form Müllerian mimicry rings, as they are strongly defended, are generally agreed to be aposematic, have similar conspicuous patterns and coloration, and are found in overlapping territories.
Aposematic mammals in the families Mustelidae, Viverridae, and Herpestidae have independently evolved conspicuous black-and-white coloration, suggesting that Müllerian mimicry may be involved.