What is the greatest competition of all time?

A man on mars? (Or women, transgender, transsexual, bisexual, gay, straight, one legged, one armed, three eyed, big toed little toed, a whisper, a whim, a cloud, a silly grin!..............)

Rugby
And alot of the gladiators were women although that's not really something to be proud about in any way

Slade's battle with Wizzard to get the Christmas number one in 1973 (Slade won).
[youtube=https://www.youtube.com/watch?v=i4BTYiy0Qi4]
[youtube=https://www.youtube.com/watch?v=bnczB6LXkqE]

Hot dog eating competition at county fairs

Any kind of one on one combat sport.

Dumbledore and grindelwald

Survival of the fittest.

arena football