I rolled a Shadow Priest and got to about level 52 and EPL/WPL and for some reason had a huge break. I then came back and got to 60, quite late compared to most. My first raiding guild was a total nab fest and I cleared some of the MC content etc. I recall getting some epic loots from the outdoor boss Kazzak when attending with my IRL friend who was in a much better guild. Got some left over cloth pieces

Was good for Holy as I could not raid as Shadow. I recall killing C'Thun in AQ40 and it was the best feeling ever. Outdoor PvP was my bag as a Shadow Priest with gear though, Warriors would run in absolute fear...as would pretty much anything.
I slowly progressed through some guilds and ended up clearing BWL etc but was never even near the hardcore spectrum. nearing the middle/end of Vanilla I was frequently playing Shadow in raids and supporting the Warlock teams in 40 mans. Cleared AQ20/40 as they became available in much the same time scales.
Stuck with the same bunch in The Burning Crusade and cleared most stuff in about average time scales. I joined Last Resort on Kazzak and started raiding hardcore, clearing Sunwell Plateau in the World Top 5 and getting the first legendary Bow Drop from Kil'jaeden - Was epic times. When Arena competative play came out I formed a 2v2 team with a Warlock whilst playing Shadow Priest. We Ranked Number 1 in 2v2 and high enough ranked in 3v3 and 5v5 to get Armored Netherdrakes in all 3 brackets. Had to delete the other 2 in my mail.....FML Unique! I am still bitter, in Season 2 they introduced PERMANENT Rank 1 Gladiator titles. My Rank 1 Season 1 title disappeared
WoTLK came and I continued in Last Resort,things slowed down for me due to IRL and having cleared Ulduar on the hardcore level quit.
I rejoined towards the end of WoTLK in a different guild but played a Protection tank. Cataclysm with another guild as tank but eventually ended back in Last Resort towards the tail end as a Shadow Priest but as more of a casual player. Cleared Cata but quit before The Firelands expansions, not gone back since.
I find it hard to go back now, I miss the hardcore cutting edge raiding and soul destroyingly hard encounters (Such as full pre-nerf M'Uru with spell pushback and everything). For a long time I played absolute high end Shadow Priest with the best gear available, the best min-max spec and the best theorycraft. Posted far too much on Shadowpriest.com and had some pretty epic official Forum posts too. I do miss it. I could DPS like a train and enjoyed competing on the worldwide raid based damage charts. A true utlity/DPS powerhouse. The same thing just is not possible these days, and I find playing casually hard, I have a drug like addict itch for the super hardcore play.