#!/usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

my %hoa = (
    flintstones        => [ "fred", "barney" ],
    jetsons            => [ "fred", "jane", "elroy" ],
    simpsons           => [ "homer", "marge", "bart" ],
);

my @freds = grep { $hoa{$_}->[0] eq 'fred' } sort keys %hoa;

print Dumper \@freds;