WWE.com recently had a piece on the wrestlers with the most tenure in WWE. Some of them are not surprisingly, but a few at the bottom were a shock to me at least.
Here is the top ten:
1) Undertaker (24 years)
2) Triple H (20 years)
3) Mark Henry (19 years)
4) Kane (17 years)
5) The Big Show (16 years)
6) Randy Orton (13 years)
7) John Cena (12 years)
8) Rey Mysterio (12 years)
9) The Miz (9 years)
10) Layla (8 years)
Note that Christian debuted in 1998, but spent a few years in TNA so his stint is not consecutive.
