I think the answers provided in earlier comments cover a great deal of the seminal researchers in our field. I would add that if you refine your search a bit--what specific topic within social psychology are you researching--that might enable the community to give you a more directed list.
Within the field of Symbolic Interactionism approach (which some scholars have analyzed as related, complementary or even conflicting to Mosovici's 'Social Representations Theory'), there is a classic text: Social Psychology, by Alfred R. Lindesmith, Anselm L. Strauss and Norman K. Denzin.
I've noticed that their names are not included in the lists previously provided. I think the reason is that -as J.R. Torregosa explains in the prologue of the Spanish traduction of the 8th edition of the book-, the symbolic interactionism approach is a "sociological social psychology".