How long is the biggest shark even excint ones?

The biggest shark that has ever existed is the megalodon. The megalodon lived about 23 million to 2.6 million years ago. Scientists estimate that some megalodons may have reached up to 18m in length, more than double that of the largest contemporary sharks; this would make it one of the largest fish (as well as largest extinct chondrichthyes) to have ever lived.