Curate, connect, and discover
1. Tom Riddle: murders, student endangerment, using a deadly creature as a weapon, framing an innocent for his crimes, manipulation of others, encouraging delinquency, school rule breaking and creating a horcrux.
2. Sirius Black: attempted murder, frequent harrasment and bullying of a vulnerable student, intimidation, school rule-breaking, illegal animagi transformation, unauthorized surveillance of staff and students, using an illegal spell, risking his friend's future, belittling his friend.
3. James Potter: attempted sexual assault, frequent bullying and harrassment of a socially vulnerable student, hexing of other students, coercion, threatening, school rule-breaking, illegall animagi transformation, unauthorized surveillance of staff and students, using an illegal spell.
4. Draco Malfoy: multiple attempted murders, affiliation with a terrorist group, repeated use of hate speech, abuse of power, use of an unforgivable curse, school rule-breaking, bullying and intimidation of others, assisting malicious prosecution of an innocent animal.
5. Peter Pettigrew: enabling and participation in rule breaking and unethical behavior, bullying, illegal animagi transformation, unauthorized surveillance of staff and students.
6. Severus Snape: school rule-breaking, use of hate speech against his best friend, affiliation with an extremist group that hates his best friend and practices dark magic on students, invention of a dark spell, ignoring Lily's valid concerns about the company he kept.
7. Hermione Granger: kidnapping and blackmailing of Rita Skeeter, assisting identity fraud, illegal brewing of a potion, theft of ingrediences, school rule-breaking, arson, assisting a prison break, disfigurement of another student, physical assault, unlawful entry of the Ministry, emotional neglect in favor of appeasing Dumbledore.
8. Harry Potter: attempted involuntary manslaughter, physical assault, identity fraud, school rule-breaking, international law violations, aiding a fugitive's escape, theft of ingrediences, invasion of privacy, spying and stalking, unauthorized surveillance of staff and students, unlawful entry of the Ministry.
9. Remus Lupin: continuous enabling of rule breaking and unethical activities, avoidance of responsibilities and duties, unauthorized surveillance of staff and students, allowing a student be harrassed.
10. Fred & George: endangering of students through reckless behavior, unethical experimentation on underage students, school rule-breaking, unauthorized surveillance of staff and students.
11. Ron Weasley: international law violation, identity fraud, assisting illegal brewing, theft of ingrediences, school rule-breaking, emotional neglect in favor of appeasing Dumbledore, betrayal of trust, unlawful entry of the Ministry, enabling of reckless behavior.
12. Lily Evans: dismissing her friend’s struggles, classist behavior towards a vulnerable student, close association with individuals known for illegal behavior and immoral actions towards her ex friend.
The reason some individuals who committed more crimes than others are ranked lower is that I took intent and ethical justifications into consideration, as well as my personal feelings about their actions. Hopefully, I haven't missed anything important.