payees
List the unique payee/payer names that appear in transactions.

_FLAGS

This command lists the unique payee/payer names that appear in
transactions, in alphabetic order. You can add a query to select a
subset of transactions. The payee/payer is the part of the transaction
description before a | character (or if there is no |, the whole
description).

Example:

$ hledger payees
Store Name
Gas Station
Person A