Elections determine the composition of legislatures, but the study of legislative representation has long been hampered by limited individual-level data on legislators. Recent innovations have vastly increased opportunities for studying legislators, but often have limited historical coverage. We introduce the Danish Legislators Database (DLD), a database of members of Denmark's parliament, Folketinget, for every electoral term since its inception in 1849. Relative to most existing databases, the DLD is rare in covering the entire history of a parliamentary body going back more than 170 years. The DLD thus enables analyses of parliamentary representation with full temporal coverage. We describe the development and content of the DLD and present a set of analyses illustrating the potential uses of the database in the study of representation.