These days, most (all?) airliners require 2 pilots at any given time. However, until the 1980s, many airliners required more crew on the flight deck than this (5 for the Lockheed Constellation and 3 for the 747 models). The AN-225 (first flight 1988) is unique in having 6 flight crew members (related).
I'm interested in knowing if there are any modern aircraft (airliners and other types) that require 3 or more flight deck crew. For the sake of the question, let's limit "modern" aircraft to those which first flew after the year 2000. Spacecraft and spaceplanes don't count - atmospheric vehicles only. Sometimes there are more than 2 pilots on board for long-haul flights, but I'm interested in the minimum flight crew for the most basic flight.