Greek, Russian, and Turkish represent three different types of null subject languages: Greek is characterized as a strict pro-drop language; Russian is claimed to be either a partial pro-drop, or a non-pro-drop language with abundant subject ellipsis; Turkish is classified as a pro-drop or topic pro-drop language in which overt subjects are required in unspecified contexts. This chapter reports results from corpus-based studies exploring the question of whether subjects in heritage varieties of these three languages in contact with English and German pattern alike regarding the realization of overt subjects. Moreover, the chapter examines whether heritage speakers of these three languages apply topic drop more widely in one of their majority languages, namely German. We consider different possibilities for our observations reaching from language contact effects, to language internal dynamics and most importantly a typological continuum within the different pro-drop types regarding the stability and dynamicity in their pro-drop systems.