For years and years people believed Luigi could somehow be unlocked in Super Mario 64, hence the "L is real" meme.

The leaked Nintendo betas revealed that Luigi had an actual model in Super Mario 64 at one time, as part of a planned 2-player feature. It was later dropped and his model was deleted from the ROM entirely.

After all these years, we finally found the unused Luigi model, glorious, glorious Luigi

So he IS real.

After years we finally have the proof we knew in our hearts