Can Saitama from One Punch Man be killed by the Death Note?
No, because no one knows Saitama’s last name.
That’s what the shinigami eyes are for.
So, yes, the Death Note can kill him.
Except you’re forgetting one thing. If the deathnote cannot kill in circumstances that are possible for the victim to die, it will default to a heart attack. Saitama cannot be killed by a heart attack and no sittuation fabricated could possible kill him so nothing will happen.