5+1 Times the Halo saved the day
Following Guanyu Zhou's horror crash at the start of last weekend's British Grand Prix, let's remember some moments since the introduction of the halo, that made us feel grateful the FIA brought it into the drivers' lives, and made us wish it had been brought sooner.

Guanyu Zhou was collected by George Russell's Mercedes, after the Brit was tagged on the rear by Pierre Gasly, in an overtaking attempt during the race start. Zhou's Alfa Romeo was flipped and sent directly into the barriers, getting trapped between the Armco and the fence. Hadn't it been for the halo, Zhou would most likely be severely or even fatally injured.
The halo got introduced in some tests in 2016 and during the 2017 pre-season testing for the first time, and was made mandatory from the beginning of the 2018 season on all Formula 1 and support series cars, including F2, F3, F4, FR and FE cars.
It's sad to see how many drivers couldv'e been saved, if the halo was brought as a safety measure earlier. Starting with Herny Surtees who lost his life during a GP2 race in Brands Hatch in 2009, and of course Jules Bianchi who crashed his Minardi under a crane during the 2014 Japanese Grand Prix.

Felipe Massa also had a horror crash during the 2009 Hungarian Grand Prix, when a 800 gram spring flew off Rubens Barichello's car and landed directly on his helmet, leaving him unconscious.
Massa suffered a brain contusion, fractures to his forehead and the base of his skull, while a titanium plate fitted to cover a gap in his skull.
So, let's remember five times the halo saved a driver from being injured:
Roy Nissany - Formula 2, 2022 British Grand Prix

Last weekend's British GP had not one, but two incidents in which the halo played a life-saving factor.
Roy Nissany made contact with Dennis Hauger on the second lap of the F2 Feature Race on Sunday, with Hauger sustaining a puncture, going off the track, over a sausage kerb, landing on top of Nissany's car.
Both drivers escaped the crash unscathed, with the motorsport community praising the halo once again, and highlighting the danger sausage kerbs inflict.

Alex Peroni - Formula 3, 2019 Italian Grand Prix
Racing in Formula 3 in 2019, Alex Peroni went over a sausage kerb at the apex of Parabolica in Monza, resulting him to land on the fence at the exit of the corner.
The Australian Campos driver retired from the Championship and returned to his homeland to recover, as he suffered a broken vertibra during his terrifying crash.
Charles Leclerc - Formula 1, 2018 Belgian Grand Prix
Just a few months after the halo was made mandatory for all F1 cars, the motorsport community was once again shook, after the crash Charles Leclerc suffered on the opening lap of the Belgian Grand Prix in Spa.

Fernando Alonso's McLaren flew over Leclerc's Sauber, after the Spaniard was hit by Niko Hülkenberg. Alonso's front right wheel brushed off Leclerc's halo, leaving visible marks on it. Hadn't it been for the halo, Leclerc would most likely have suffered severe, probably fatal, head injuries.
Lewis Hamilton - Formula 1, 2021 Italian Grand Prix

As the 2021 championship battle between Max Verstappen and Lewis Hamilton went on, the two clashed in Monza, with neither of the drivers finishing the race.
Max Verstappen went over a sausage kerb at T2, landing on Hamilton's Mercedes, with his rear right tyre pressing on the Brit's head. Hamilton suffered some neck pain from the incident, and would sustain way more serious head and neck injuries if the halo wasn't there.
Romain Grosjean - Formula 1, 2020 Bahrain Grand Prix

Just three races before the end of the 2020 season, one of the most terrifying crashes we have witnessed in a while took place in Bahrain.
Romain Grosjean, after some Lap 1 contact with Daniil Kvyat, went through the barriers of T3, with his Haas splitting in half and catching on fire.
The Frenchman escaped the 67G ball of fire without any life-threatning injuries, with burns on his hands and feet, as well as a left ankle fracture.
Removing the halo from the equation, Grosjean would've sustained fatal injuries, with his head being completely exposed to the barrier.