L3-37 is a character mentioned in Fallout 4.
L3-37, now known as Leo, is a runaway synth in 2287. They were harbored and physically altered by the Railroad. The Institute sent many coursers to bring them back, including X9-73, without success.
L3-37 is mentioned only in Fallout 4.
Behind the scenesEdit
The designation "L3-37" is an obvious gag reference, as it translates to "Elite" in 13375p34k, and appropriately describes a synth able to handle multiple coursers without trouble.