Pete Twist's underpants (Round the Twist); via exposure in microwave
Korosensei (Assassination Classroom) is capable of flying at speeds up to Mach 20.
In her full Apostle form, Rosine (Berserk) could fly at supersonic speeds.
Washio (Buso Renkin) can fly at supersonic speed, appearing as a bolt of light when he does.
The Kinto'un (Dragon Ball) can fly faster than even a jet.
Krillin and Son Gohan (Dragon Ball Z) use Dragon Dash to greatly enhance their flight speed.
Piccolo (Dragon Ball Z) using Dragon Dash to greatly enhance his flight speed.
Tien Shinhan (Dragon Ball Z) using Dragon Dash to greatly enhance his flight speed.
Shin Feiuruku allows Ashuron (Zatch Bell!) the ability to fly at an incredibly high speed. In fact, with this spell, Ashuron is moving faster than the speed of sound.
Danny Fenton/Phantom (Danny Phantom)
Dawnstar (DC Comics) can fly at supersonic speed.
Superman (DC Comics)
Waverider (DC Comics) can fly at the speed of light.
Animal Man (DC Comics)
Wonder Woman (DC Comics)
Starfire (DC Comics)
Raven (DC Comics)
Billy Batson/Shazam (DC Comics)
Night Furies (HTTYD) are known as the fastest dragons on earth, capable of breaking the sound barrier. However their tailfins are their main source of their flying ability, and altering it can change its abilities in speed. Even in average flight speed they fast with several dragon species rivaling the average speed.
The Powerpuff Girls (The Powerpuff Girls) can fly fast enough to accidentally travel fifty years into the future...
...and make tornadoes.
The Rowdyruff Boys (The Powerpuff Girls)
Splendid (Happy Tree Friends) flies fast enough to create a sonic boom.
Discord (My Little Pony: Friendship is Magic) flying supersonic.
Rainbow Dash (My Little Pony: Friendship is Magic)
Monica Rambeau/Spectrum (Marvel Comics)
Wendell Vaughn/Quasar (Marvel Comics)
Sam Wilson/Falcon (Marvel Comics) saving Captain America in a split second.
Thor (Marvel Comics)
Sentry (Marvel Comics)
Johnny Storm/Human Torch (Marvel Comics)
Jim Hammond/Human Torch (Marvel Comics)
Carol Danvers/Captain Marvel (Marvel Comics)
Simon Williams/Wonder Man (Marvel Comics)
America Chavez (Marvel Comics)
Ultimate Way Big (Ben 10 Series)
Johnny Storm/Human Torch (Fantastic Four) can fly faster than a missile.
Tony Stark/Iron Man (Marvel Cinematic Universe)
Kara Zor-El/Supergirl (Arrowverse)
Mari McCabe/Vixen (Arrowverse)
Superman (DC Extended Universe)
Miles "Tails" Prower (Sonic the Hedgehog: The Movie)
Jetstream (Sky High) main power is to fly faster than anything on earth.
King Ghidorah (Godzilla series)
Sonic, Shadow, and Silver (Sonic the Hedgehog) can fly at incredible speed, even in the vacuum of space via their Super Forms.
Valphalk (Monster Hunter Series) can fly at supersonic speed, making him look like a giant red comet.