The most epic opening theme in TV shows

Stargate SG1
Fringe... EPIC
Boy Meets World (Nostalgia)

Boardwalk Empire

There is a lot of great, but this one - Utopia - it's haunting! Along with the show itself - it's fantastic but sadly unknown. So fix this unfortunate fact. It's acid British show about conspiracy filled with paranoia and... and what else do you need? Go watch it already!

Air Gear

Not a tv show, but totally worth it.

This gives me shivers down my spine

Jayce and the Wheeled Warriors - https://www.youtube.com/watch?v=14C9hySGfWw

Family Matters

why noone mentioned Friends? ;_;

KNIGHT RIDER! https://www.youtube.com/watch?v=RhRhH--xOPQ

Kindred: The Embraced (short-lived white-wolf basd Vampire TV show)
Intro 1 (not a great copy) - https://www.youtube.com/watch?v=5gRGS0CHQHM
Intro 2 (alternate) - https://www.youtube.com/watch?v=_gtDbdR2doU

These are undoubtedly the greatest opening sequences ever made, because Star Wars + TV opening = awesome. Pity he didn't make more.

Also Thunderbirds, The Muppet Show, Sledge Hammer,

Vikings is also worth mentioning: https://www.youtube.com/watch?v=gmyCRJkKeKs

POKEMON GONNA CATCH THEM ALL!