In this paper, we examine surnames that serve as markers of identity among some Yorùbá sub-ethnic group members. We show that this present work is different from the previous works because the earlier works focused on Yorùbá personal names in general, and the present work locates the Yorùbá surnames within particular sub-ethnic groups to show that though all the names described in the previous works are Yorùbá names the previous works do not distinguish tradition-based names that are today surnames and also do not tell us where the names can be found within the Yorùbá sub-ethnic groups. We argue that surnames form one of the parameters that can be used to distinguish the Yorùbá sub-ethnic group members from one another. We also show that surnames which indicate Yorùbá sub-ethnic group affinities are tradition-based personal names and that each of the tradition-based surnames is structurally a combination of a noun phrase and a simple clause or a noun phrase and a simple clause. We further show that the noun phrases depict traditional religions or deities that were peculiar to each sub-ethnic group before the advent of Christianity while the simple clauses, in some cases, consist of lexical items that are also peculiar to each sub-ethnic group dialect. We also argue that the introduction of Western or European address forms into Yorùbá whereby the use of surnames is emphasized has helped in preserving the Yorùbá religious thoughts, beliefs and variation in Yorùbá dialects. This is because, in some cases, the tradition-based surnames serve as reminders or are full of reminiscences of the religious activities of the Yorùbá people before the advent of Christianity in Yorùbá land.