Code Geass
This is probably the classic Death Note recommendation because both center on a genius antihero using a supernatural power to reshape the world. Fans who liked Light's mind games usually enjoy Lelouch's chess-like planning, secret identity, and morally messy rebellion.
Monster
Monster is slower and more grounded, but it shares Death Note's cat-and-mouse tension, moral philosophy, and obsession with whether one person has the right to judge another's life. It is a better match for fans who liked Death Note's psychological pressure more than its supernatural rules.
Kaiji: Ultimate Survivor
Kaiji trades murder notebooks for gambling death games, but the core appeal is similar: constant mental traps, desperate deductions, and high-stakes psychological warfare. It also has that same feeling of watching someone survive by reading people under impossible pressure.
Psycho-Pass
Both shows question justice, punishment, and whether society should let a system decide who deserves to be removed. Psycho-Pass leans cyberpunk and police procedural, but the philosophical conflict between order and free will lands in a very Death Note-friendly zone.
One Outs
One Outs is a sports anime on paper, but community recs link it to Death Note because it is really about manipulation, prediction, and psychological dominance. If someone liked Light and L's tactical back-and-forth, Tokuchi's mind games give a similar thrill in a baseball setting.