There are quite a lot of compilations released along the years.
Official but also unofficial. These are great items to collect.
Click on the title to visit the collection-page.

The Candlelight Years
Compilation of the first three albums which were released through the Candlelight recordslabel

The Wooden Box
Compilation of the first three albums on vinyl in a nice wooden box, released by Viva Hate Records

Deliverance & Damnation "Remix"
Both albums were remixed and bundled into one release in 2015

Diverse Compilations

Various Album Compilations

Sampler compilations

Compilation dvd's

Russian Compilations