The Monster Seats at Fenway Park are the famous seats located high above the Green Monster in left field. For your best chance at a home run, choose seats in M2-M6. Even if you don't catch a ball, you'll get a great look at fly balls and balls played off the Green Monster.
Reserved Monster seating will feature barstools with a ledge, while SRO ticketholders will have no seat, but will have the opportunity to stand against a ledge if you arrive early enough.
Unfortunately, sitting in these seats will have you exposed to the sun and unable to see the scoreboard in center field.