For 20 years now, Syfy – starting from when it called itself SciFi – has been presenting New Year’s Eve marathon showings of The Twilight Zone. This Rod Serling showcase is one of the most tenured TV marathons around, and with good reason: Whether the show is a classic you know by heart or an obscure episode you’ve somehow managed never to see until now, every single program pulls you into the Zone, in the very best way. The two-day marathon begins this morning. Today’s highlights include a great block beginning at 7:30 pm. ET, in which “The Monsters Are Due on Maple Street” (pictured) leads into, in succession, “The Dummy,” “The Invaders,” “To Serve Man,” “Nightmare at 20,000 Feet” and “A Stop at Willougby” – each and every one a classic.