The short answer would be the whales/pumpers/shills, but that would not be entirely true, because every person buying or selling any Crypto currency has a influence on the market.
We also cannot discount the influence of the many news media platforms that are being used to manipulate the price too, because they are one of the tools that are used by whales/pumpers/shills to control the markets.
Most of the larger exchanges are used as a benchmark/data source for the global price, so we should give them credit too.