During fall '19 players started finishing their complete collection of followers from the Warlords of Draenor Garrison. WoD was released in November '14 and it takes about 5 years to collect all followers. I made this little video to show what it looks like when you’re done:
Unfortunately, there is no reward, easter-egg or cow level for completing this. 
5 years? For which follower?
I have no idea what follower would take five years to gain. I had more followers than could be active.
In any case well done 
There are 299 followers in total, 56 of which you can collect through quests, vendors, achievements and missions. The remaining 243 followers are collected one by one, once per week, from the Lunarfall Inn / Frostwall Tavern.
I honestly had no idea there were that many.
I don’t think a lot of players do. It’s a completionist / niche thing to do.
I finished it about four weeks ago. Got them all to epic and max gear last week.
Holysh*t, dude. That is some dedication right there. I wouldn’t be able to do this even if there was a reward at the end of it.
I’m surprised it doesn’t have a FoS
“What Could Have Been…”
That’s phenomenal, I had no idea there were that many followers like others have said, such a shame you don’t get any reward.
But congratulations it IS an achievement.
299???
Holy crap…and u maxed all to epic?
It’s good it doesn’t have any achivement - some completionist will piss off for such grind.
Anyway Congo…!!!
299 is only for people who did the legendary ring quest line and received Garona legendary follower.
Well I don’t think Blizzard ever considered many people would want to do something that crazy.
Still It took me half of this time to get Worgen follower in every single active follower slot. That was also a crazy idea, also bit of a racist one.
Blizz should know by now, someone will always do that kind of crazy 
Thats a new level of crazy!
I have a friend who refused to use anything but Goblin followers. You guys make that look pedestrian.
Yeah, well once you’re into recruiting every week, leveling followers to epic and maxing out their weapons & armor sort of comes for free. The only difficult thing about this it is the persistency and patience, since in the end, you get nothing but an empty recruitment board.
I tried to use only non Alliance followers on this character…I succeeded too until Allied Races came out. Now I have to replace the DI Dwarves!LOL
Most of my other characters tried to stick to the same race followers though.
Grats on getting them all. The Pokemon Garrison Achievement! 
I collected them all but only Night Elves are active - and guarding the place.