#8 Ayrton Senna - Brazil 1988
Ayrton Senna received a black flag at his home Grand Prix in Brazil. After a mechanical failure in his first-choice car at the start of the race, the Brazilian started the race from the pits using his spare car.
Later in the race, Senna was shown the black flag for changing his vehicle after the race was green-flagged at the end of the formation lap. The setback in the very first race of the season did not matter as the prolific Brazilian went on to win the 1988 world championship.
#7 Juan Pablo Montoya - Canada 2005
The Colombian racing driver received his second black the following year at the Canadian Grand Prix. Montoya had a productive qualifying session and started the race from the fifth position.
Driving the McLaren, the Colombian led for a decent portion of the race until the introduction of a safety car on lap 49. Montoya had to give way for his teammate Kimi Raikkonen to pit earlier forcing him to pit the next lap, which ensured that he would lose the race lead at the restart. A lapse in judgement caused Juan Pablo Montoya to exit the pitlane with the red light flashing. Immediately following the restart, the McLaren driver was under investigation and was later black-flagged by the stewards on lap 52.