Join The Fan Lab, a private Fandom research community for users in the US and UK where you will be asked to share your opinions on all things gaming and entertainment! Click here to see if you qualify
L3-37 was an escaped synth assigned to X9-73 for recapture. L3-37 was mem-wiped, given the identity "Leo", and last seen at the Corvega assembly plant, where it has managed to evade capture twice using weapons skills learned from The Railroad.
L3-37 is mentioned only in Fallout 4.
Behind the scenes
L337 is one variation of the word leet; the method of forming words using numbers and other characters, also known as 1337 or leetspeak.