Shihaisha no Tasogare

Both anime are animated by Madhouse and where release in a similar time period (late 90's-early 2000's). Both anime feature a main protagonist who hunts various nightmarish creatures. Both are action-packed anime with blood and gore. They also have a similar dark and gothic atmosphere. If you like one, you will enjoy the other. 

The main protagonist in both anime are white hair demon hunters that fights against powerful demons. Both anime have character designs designed by Hisashi Abe and are also animated by Madhouse. They also share a similar dark and gritty atmosphere filled with action, violence, blood and gore. If you enjoyed one, you will enjoy the other.  

Both of an older animation style and demons-related plot, they have a similar dark, mysterious feeling to them; both with a big potential to make full-lenght series. Also, Tsunami somehow reminds Count D, the more so because they have the same seiyuu. 

Two titles from the end of 90's featuring demon-hunting detectives. 

both are dark toned series that focuses on a lot of supernatural shit and mythos as well too and also messed up looking demon designs and nice looking art and visuals as well too. 

Science fiction, demons, monsters and action are key defining factors for both anime. Shihaisha no Tasogare is more brooding and slow-paced, Cyguard has more action and power metal soundtrack... But both are very similar in style. 

Similar in atmosphere and style, another dystopian anime. 

Another short OVA that is similiar style in animation. Not much character development in either. Both seem like a segment of a larger B movie. 

Similiar style of animation. BioHunter has more of a story and doesn't feel like it's a segment of a longer movie like TotDM. 

Both titles are horror anime that place in Shinjuku and are animated by Madhouse. The main protagonist in both anime must battle against demonic forces trying to destroy humanity. Both titles have a similar dark and gritty atmosphere. As well as similar art, animation and a similar vibe. If you like one, you will enjoy the other.