The 20 most common name in the genealogical database:

Rambow family = 1372 people
(Rambau, Rambeau, Rambach, Rembowski etc.)

Liesegang/Leisegang = 1059

von Bulow / 292
Engelbrecht = 292
Litzmann = 283
Hattorf /von Hattorf = 283
von Bistram = 276
Brandis = 269
Alemann = 257
von der Osten = 252
von Kleist = 234
von Normann = 234
von Hugo = 231
Schrader = 211
Luther = 204
Meyer = 192
Bötticher = 192
Tappen = 190
von Arnim = 185
Spangenberg = 182