The Lorimer Burst
The first FRB to be identified was the so-called Lorimer Burst. After its primary detection beam became saturated, the Parkes multibeam detector picked up the radio burst. This suggested that the burst occurred between the beams, necessitating a very high peak flux density. Since it displays higher fluence than the majority of the fast radio bursts that have been identified since its detection, this FRB is still regarded as one of the "brightest" ones.
This FRB could be the result of a pulsar emitting gamma rays in the direction of the Large and Small Magellanic Clouds, according to one theory, although the origin is still a mystery.