You'll have to reach Forsaken Castle Cainhurst to find this. When you do, move through the castle until you cross a long hallway with a single enemy. When you get back outside, take the next right down a dead end. You'll find two gargoyles guarding the garb, gauntlets, and trousers.
You start the game with this.
The full set can be purchased with Insight in Hunter's Dream after defeating Father Gascoigne.
The graveyard set is a little tricky to find. In the Forbidden Woods, you'll eventually reach a riverbed area filled with snake enemies. Follow the river until you face a particularly large version of these guys. Take him out, then continue forward. Listen for one of the large pig enemies and look for him atop a hill. He's guarding the fallen tree you see in the screenshot above. Take him out, cross over the tree, and look to the left to find the set.
Gray Wolf Cap
Can be purchased with Insight in Hunter's Dream.
Henryk's Hunter Set
Can be purchased from the Bath Messenger after helping Eileen the Crow kill Henryk.
Iron Yahar'gul Helm
Can be found just past the Yahar'gul, Unseen Village lantern. Take a right at the fork, then follow the stairs down to a rotunda. The helm is on corpse leaning up against a statue.
The knight garb, gauntlets, and trousers can be found in the second part of the library in Forsaken Cainhurst Castle. It's in a chest in the back left corner from the entrance - walk around the long table to reach it.