Might I suggest some categories? I have included my choices* for said categories also…
Most Rousing - Star Trek TNG/Dangermouse
Most sing-alongable - Red Dwarf/Ulysses 31/Fraggle Rock
Most lullabyish - Twin Peaks/Father Ted/Arena
Most 80’s - Street Hawk/Airwolf
Most bestest cartoon/animation theme - Count Duckula/Trapdoor
*subject to change as I remember other theme tunes…
Has it been done before? Danmit. I’m sure @btripz will dig it out if we’ve done it before!
I’ll change the terms of the debate a little then - it has to be a theme song that you could conceivably do at a (terrible) karaoke night. No instrumentals! Banana Splits qualifies as it has lyrics. All others so far can fuck off.
Maggie Bell is blasting out a tune in The Hazel Theme FFS 
Dambusters, Star Wars, Great Escape…
Oh the OP meant TV Shows.
So how about shows where you know what it is inside about two bars
Dr Who
Monty Python.
GoT
Oh sorry still no actual definition of what constitutes the greatest…
What about Ski Sunday? or the old F1 Music (By Fleetwood Mac)
The perfect never ending thread this one so many themes
If it has been done then I am unaware of it, even my brain the size of a planet forgets things occasionally.
And changing the category restricts things massively, not many theme tunes have lyrics so, in essence, you are stuck with the Muppets or the Banana Splits of Fraggle Rock. Unless you consider me beat boxing the timpanis from 2001 : A Space Odyssey as karaoke?
Whils strictly not a theme tune
One of my criteria for tunes that qualify as the best would be, ‘do you listen to the full theme tune even when binge watching episodes?’, this one defo qualifies 
Oh yeah, quantum leap!
Technically.
Being boring.
White Christmas is the official best theme song ever in that it has sold more than any other single - 50 million
Whitney is also up there with the theme from the Bodyguard (obviously being a male dominated forum nobody else will ever mention that one) - 15 million
And then there is Unchained Melody - theme from Ghost
Or just have a list
Oh look lots on here we’d never notice!
Meanwhile
What about the ACTUAL James Bond Theme? (Sidestepping the argument about which of those was the best)
I have to drag the local connection in and suggest Howards Way…the opening theme…
and the up tempo closing theme…
