use strict;
use warnings; 
use 5.012;  #for say()


my $text = "Enter Iago, Othello, and others";

while ($text =~ / 
                  \s+      #A space one or more times 
                  (        #Start of $1
                    [^,]+  #Not a comma, one or more times 
                  )        #End of $1
                  ,        #A comma
                /gxms      #(g)lobal matching plus standard xms
) {
    say $1;
}


--output:--
Iago
Othello