Berlin Westkreuz is a station in the Charlottenburg district of Berlin. It is served by the S-Bahn lines S3, S41, S42, S46, S5, S7 and S9 and so represents a major interchange point on the Berlin S-Bahn network. It lies at the opposite end of the Stadtbahn to Ostkreuz and is one of the four main stations on the Ringbahn.

S3 is a line on the Berlin S-Bahn. It operates from Erkner to Spandau. For most of its existence since becoming a numbered route in 1984, the S3's line colour is blue.