Vanilla - I was a few weeks late into the game, but played a rogue. Leveled up to 60 and found a few friends, we created a guild together on Haomarush. One thing led to another, and before long, we had "absorbed" a whole bunch of smaller guilds into our own and started raiding.
Nothing special to write home here about, we wern't cutting edge raiders, and our progress was steady, working our way through the raids. The first *big* guild moment came when we got our first thunderfury, which, went to a rogue

Quite litterally we must have had the entire realm turn up to kill thunderaan, it was epic.
Moving up through BWL and AQ40 nothing much to note, then we hit naxx, oh the resistance gear grinding... even now makes me shudder thinking of it.
Basically cleared everything through to the 4 horsemen, never got the kill before the TBC patch and everyone went to battlegrounds for the easy epic gear.
Only other point of mention was I helped a friend grind high warlord on his warrior. We litterally played shifts, for 7 days a week, 24 hours a day... on the final week he needed.
TBC
We started off strong, clearing heroics, getting attunements sorted etc. Early raids such as kara, gruul, mag were easy. We got all the doom lord and lootreaver kills also on our realm.
SSC was hard for us as we geared our tanks up for the hydros resistance gear, then the main tank got banned. FML.
Finding a new good tank at this point was pretty hard, but we managed eventually by absorbing another guild and their top players, and then powered through TK and SSC pretty quickly. Never saw ashes drop in TBC.
Hyjal was fun, we had a maintank pala who just carried us on this. It was also here I re-rolled to priest. Cleared Hyjal and went BT. Again, we had solid steady progress, nothing to write home about, apart from on our first and third illidin kills, got warglaives, first on the realm to have a complete set (yes we used the loot table bug to get them, get over it

)
After farming BT for months, and even started selling warglaives for IRL cash to buyers, Sunwell came.
At sunwell we had had a lot of player turnover in BT, and didn't realise how low quality our roster had got, never killed brutalus, the guild disbanded and I transfered realm to a new guild who was progressing on felmyst.
We did alright, getting upto muru.... oh muru... killer of guilds... now that was an AMAZING fight of fights as a healer, I loved it, CoH spam anyone? KJ was also, simply an amazing fight, we were one of the top guild at the time who got KJ down after the soul flay nerf. I was one of the people at WWI08, who gave a small demo of priest healing in sunwell
WotLK.
Having played DK at WWI08, I knew I was re-rolling DK. So I did.
Joined up with The Legacy, cleared WotLK upto the end of Ulduar with top world ranks, then the guild disbanded (or good as). Got all the realm firsts, deaths demise, celestial defender etc etc etc.
Joined up with Apex for ToC and ICC, I was the first DK in the world to reach maximum gearscore. S'mourne + full heroic items.
Cata - I played half heartedly, it was
****. Still got good ranks, joined method, finished the game and then quit due to how boring it was.
Mists - Came back and joined up with some friends, we did alright, top 50 world upto ToT. Again nothing to write home about.
Now playing on a new guild on EU-Ragnaros. It's a guild of top quality players who want solid, good progress on a normal schedule. On our second week of forming and raiding SoO we downed heroic garrosh 25 man, taking the realm first.
Looking forward to WoD, we are looking to realy get noticed as a top 10 (25/20) guild, which works for people on a 9-5 job