あいつ, 彼奴, きゃつ, あやつ, かやつ
Pronoun, Derogatory, Familiar language, Usually in kana, きゃつ is masc.
he, she, that guy, that one, that thing
あいつには二度と会いたくない。
は
Particle, pronounced わ in modern Japanese
1. indicates sentence topic
2. indicates contrast with another option (stated or unstated)
3. adds emphasis