The ler are a species in books by M. A. Foster. The ler are the result of a genetic engineering experiment intended to create a race of supermen. Instead, the result was simply something different from humans, a new species that can't inter-breed with humans.
The ler customarily mate in an interesting sort of braid relationship, where four parents, 2 male and 2 female, mate in all possible combinations over a number of years to produce 4 children.
The ler possess photographic memory, and also the ability to auto-forget.