#1. Neymar

Neymar’s transfer to Barcelona and then to PSG were both under the scanner for the manner in which it happened. But let’s just stick to the Barcelona one for now.
Barcelona signed Neymar in 2013 without a lot of fuss but a few months later, stories regarding his transfer started to unravel. In January 2014, a prosecutor’s office in Madrid investigated the transfer fee Barcelona paid for Neymar and the documents submitted to the authorities contained contradictory information.
A few days later on January 23, president of Barcelona, Sandro Rosell, resigned from his position of power. A day later, it was revealed that Neymar’s transfer cost Barcelona close to €100 million and not €57.1 million as reported earlier.
It was confirmed that Neymar’s parents received €40 million from Barcelona as part of the transfer. As a result of the controversy, Barcelona and Bartomeu were charged with tax fraud.
Later, Neymar’s former club Santos filed a suit with FIFA seeking compensation for a breach of contract in the transfer of Neymar.