import re

regex = r"^[|\s]*\|\s*([^|\s]+)$"

names = ("| John | Gilbert | alan\n"
            "| Stephen | king | harris\n"
            "| | Steve\n"
            "| Barack | | Obama\n"
            "|| Donald | | Trump \n"
            "| | Alan\n"
            "| | Stewart")

print(re.findall(regex, names, re.MULTILINE))