Kyoushoku Soukou Guyver (2005), Terra Formars Recommendations
A limited number of weaponized/genetically augmented humans must defeat a seemingly endless population of engineered monsters, for the sake of humanity. Where the characters of Terra Formars are determined to exterminate highly evolved cockroaches on Mars, to stop the spread of a fatal virus plaguing earth, the MCs of Guyver stumble into a society of genetically engineered monsters, with the intent and resources to dominate humanity.
These two anime focus on a main character that can transform into something that is not human and uses his superhuman powers to fight against evil. The main character in these two anime are fighting for their lives against powerful evil aliens. Not to mention these two anime are filled with violence, blood and gore too.