I'll start with maybe the most common, The.

The Rock
The Undertaker
The Miz
The Big Show
The Great Khali
The Fabulous Moolah
The Sandman
The Hurricane
The Godfather
The Brian Kendrick
The Boogeyman
The Repo Man
The Warlord
The Anvil (Jim Neidhart)
The Iron Sheik
The Black Scorpion
The Patriot
The Red Rooster
The Great Sasuke
The Sinister Minister
The Blue Meanie
The Tazmaniac
The Cheetah Kid
The Masked Superstar
The Original Sheik
The Great Muta (often referred to as "The Great")