Nikaia (Greek: Νίκαια, Níkaia), known before 1940 as Kokkinia (Κοκκινιά, Kokkiniá), is a suburb in the southwestern part of the Greater Piraeus municipalities, Greece. Since the 2011 local government reform it is part of the municipality Nikaia-Agios Ioannis Rentis, of which it is the seat and a municipal unit.
In August 17, 1944, took place the Executions of Kokkinia. It was the largest Nazi roundup and one of the largest-scale war crimes perpetrated during the German occupation of Greece.
Nikaia, like many other places around Greece, owes its population eruption to Greek refugees who left the Asia Minor coast after the 1922 war ended. It was part of the municipality of Piraeus until 1933, when it became a separate municipality, then still under the name Nea Kokkinia. It was renamed to Nikaia in 1940.