Secret Mini Boss

Wicked K is a secret mini boss who you can fight after certain areas. He is easily missable since there are no clues or hints where and when he will show up. You can fight him 4 times, upon defeat he will give 1000 souls the first two times you beat him and 2000 for the last two times but the fight will be harder compared to the first two fights. He blocks most attacks and the best way to damage him is to use the Devil's Cross counter or the Affliction Wrath ability. And he is british.

You can do them in any order but I am listing them based on when they will be available.

The earliest encounter you can do is at The Choking Grounds. He will only spawn after you enter The Drowned Pass. He can be found under the movable grave south of Vulgrim.

Head east from the Tormented Gate walk up the dirt ramp and enter the sewer pipe he should be inside. He will spawn after you enter Anvil's Ford for the first time.

You can find him to the west near the end of the path. He will spawn after you enter The Hollow.

Only accessible after you get the Abyssal Chain. He will be in a small cave north of the entrance, just swing past the lava.