HIBP info for titanic203876:
8tracks: In June 2017, the online playlists service known as 8Tracks suffered a data breach which impacted 18 million accounts. In their disclosure, 8Tracks advised that "the vector for the attack was an employee’s GitHub account, which was not secured using two-factor authentication". Salted SHA-1 password hashes for users who didn't sign up with either Google or Facebook authentication were also included. The data was provided to HIBP by whitehat security researcher and data analyst Adam Davies and contained almost 8 million unique email addresses. The complete set of 18M records was later provided by JimScott.Sec@protonmail.com and updated in HIBP accordingly.
Compromised data: Email addresses, Passwords

HauteLook: In mid-2018, the fashion shopping site HauteLook was among a raft of sites that were breached and their data then sold in early-2019. The data included over 28 million unique email addresses alongside names, genders, dates of birth and passwords stored as bcrypt hashes. The data was provided to HIBP by dehashed.com.
Compromised data: Dates of birth, Email addresses, Genders, Geographic locations, Names, Passwords

National Public Data (unverified): In April 2024, a large trove of data made headlines as having exposed "3 billion people" due to a breach of the National Public Data background check service. The initial corpus of data released in the breach contained billions of rows of personal information, including US social security numbers. Further partial data sets were later released including extensive personal information and 134M unique email addresses, although the origin and accuracy of the data remains in question. This breach has been flagged as "unverified" and a full description of the incident is in the link above.
Compromised data: Dates of birth, Email addresses, Genders, Government issued IDs, Names, Phone numbers, Physical addresses

Poshmark: In mid-2018, social commerce marketplace Poshmark suffered a data breach that exposed 36M user accounts. The compromised data included email addresses, names, usernames, genders, locations and passwords stored as bcrypt hashes. The data was provided to HIBP by a source who requested it be attributed to "JimScott.Sec@protonmail.com".
Compromised data: Email addresses, Genders, Geographic locations, Names, Passwords, Usernames

River City Media Spam List: In January 2017, a massive trove of data from River City Media was found exposed online. The data was found to contain almost 1.4 billion records including email and IP addresses, names and physical addresses, all of which was used as part of an enormous spam operation. Once de-duplicated, there were 393 million unique email addresses within the exposed data.
Compromised data: Email addresses, IP addresses, Names, Physical addresses

SHEIN: In June 2018, online fashion retailer SHEIN suffered a data breach. The company discovered the breach 2 months later in August then disclosed the incident another month after that. A total of 39 million unique email addresses were found in the breach alongside MD5 password hashes. The data was provided to HIBP by a source who requested it be attributed to "JimScott.Sec@protonmail.com".
Compromised data: Email addresses, Passwords

Truth Finder: In 2019, the public records search service TruthFinder suffered a data breach that later came to light in early 2023. The data included over 8M unique customer email addresses, names, phone numbers and passwords stored as scrypt hashes.
Compromised data: Email addresses, Names, Passwords, Phone numbers

Verifications.io: In February 2019, the email address validation service verifications.io suffered a data breach. Discovered by Bob Diachenko and Vinny Troia, the breach was due to the data being stored in a MongoDB instance left publicly facing without a password and resulted in 763 million unique email addresses being exposed. Many records within the data also included additional personal attributes such as names, phone numbers, IP addresses, dates of birth and genders.