The Flash (8 p.m., CW) – The Season 2 premiere, picks up months after the Singularity attacked Central City, and Barry (Grant Gustin) is still struggling to forgive himself for Eddie’s death. Concerned about putting his friends in danger, Barry has pushed everyone away and has chosen to protect the city on his own. When a meta-human named Atom Smasher (guest star Adam Copeland) attacks the city, Iris (Candice Patton) tells Barry that he needs to let his friends help him protect the citizens of Central City. Meanwhile, Cisco (Carlos Valdes) helps Joe (Jesse L. Martin) with his Meta Task Force.
Muppets (8 p.m., ABC) – Nick Offerman assists the gang and Christina Applegate brings Miss Piggy a surprise. Meanwhile, Liam Hemsworth, Pepe and Rizzo help Gonzo with online dating.
The Grinder (8:30 p.m., Fox) – After an exciting victory, Sanderson and Yao is flooded with cases, and Dean wants to choose what they tackle next.
iZombie (9 p.m., CW) – To learn the details of his death, Liv eats a cantankerous old man’s brain in the Season 2 opener.
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Scream Queens (9 p.m., Fox) – As Halloween approaches, Pete and Grace visit a mysterious woman connected to Kappa’s past.
Drunk History (10:30 p.m, Comedy Central) – From drunk people, learn about how Milton Bradley made board games popular and how chess master Bobby Fischer defeated Boris Spassky during the Cold War.