The Mercedes-Benz W 21 was a six-cylinder passenger car launched in 1933 using the name Mercedes-Benz Typ 200.

It was one of several Mercedes-Benz models known in its own time as the Mercedes-Benz 200 (or sometimes, in this case, as the Mercedes-Benz Typ (e) 200) and is, therefore, in retrospect, more commonly referred to using its Mercedes-Benz works number, “W21”.

The car was a development upgrade from the manufacturer's W15, introduced two years earlier.

The W21 replaced the Mercedes-Benz W02 (in its own day known as the Mercedes-Benz Typ (e) 200 “Stuttgart”) that the company has been manufacturing since 1928.