In algebraic geometry, a Todorov surface is one of a class of surfaces of general type introduced by Todorov(1981) for which the conclusion of the Torelli theorem does not hold.
References
Morrison, David R. (1988), "On the moduli of Todorov surfaces", Algebraic geometry and commutative algebra, vol.I, Tokyo: Kinokuniya, pp.313–355, MR0977767
Todorov, Andrei N. (1981), "A construction of surfaces with pg=1, q=0 and 2≤(K2)≤8. Counterexamples of the global Torelli theorem.", Invent. Math., 63 (2): 287–304, doi:10.1007/BF01393879, MR0610540