Search some crypts/burial chambers, i found the marker for the Elder there.

boss markers are relatively rare. Eventually you stumble over it, but it can take some time. The first boss is always easy to find, but after that, its hit or miss.

I see, I thought boss markers were set in the same place for everybody but im guessing its randomized on each server? Ill keep looking anyway, thanks.

Remember to return the first boss head to the altar where you start els im not 100% sure if you can advance.
But els boss 2 is in the black forrest and if i recall correctly you find his location in the crypt with skeletons. Basicly every time you find a skeleton in the black forrest area you know there is a crypt somewhere nearby. ;-)

Boss 3 ( bonemass ) i found the location of him after visiting the swamp area and in a stone tower there was a stone with his location. ( els i think it can be found in the submerged crypt in the swamp.

ps. when you put the head on the altar remember afterwards to click the head and you get a special time limited ability that can help you with example cutting down trees faster.

Originally posted by Delle(DK):

Remember to return the first boss head to the altar where you start els im not 100% sure if you can advance.

You can. I've found the Elder's location stone before fighting Eikthyr multiple times.

Also, since no one's commented it yet: you can also find the stones showing the Elder's location at those ruined towers (the ones with multiple floors, not the tiny ones) that Black Forests are full of.
Still rare, though.

Originally posted by challitajg.12:

I see, I thought boss markers were set in the same place for everybody but im guessing its randomized on each server? Ill keep looking anyway, thanks.

this game operates off random generated maps. Each one is unique, though you can get seeds from other people to play on known maps if you want to take advantage of known special maps (eg there is one with a giant iron filled swamp 'not far' from spawn in, and others where the vendor is right there near spawn, and so on).