42 minutes is the amount of time it took for the first guild in the world to clear Blackwing Lair. The new content was opened up at 6:00 PM EST on February 12th, 2020, and guilds were racing to see who could clear it the quickest.
WoW Classic Blackwing Lair World First Clear
Calamity and Progress both cleared Blackwing Lair and defeated Nefarian at a nearly identical time. The kills were in fact so close together that it was impossible to determine a winner, so congratulations to both guilds on this accomplishment.
WarcraftLogs is processing ranks for this dungeon, but as of now here are the top guilds according to the data submitted to the site. The Blackwing Lair progress page shows this data as it updates, which reports Calamity defeated Nefarian slightly before Progress.
Progress uploaded their clear video to YouTube which you can check out below.
With less than 43 minutes elapsed, the first three guilds in the world to complete Blackwing Lair in WoW Classic were: