Attacker

Common synonyms include: aggressor, assailant, adventurous, adversaries, aggressive person, aggressors.

/əˈtækɚ/ noun

noun ·Uncommon ·College level

Definitions

Noun

1
Someone who attacks.
"[…] expecting the woman to take her attacker into physical custody is tantamount to preventing the arrest. If she could handle him, she probably would not need to call the police in the first place."
2
someone who attacks wordnet
3
One of the players on a team in football (soccer) in the row nearest to the opposing team's goal, who are therefore principally responsible for scoring goals.

"He wrestled his attacker to the ground."

From attack + -er.