May 15 is the 135th day of the year (136th in leap years). There are 230 days remaining.
- 1827 — Beta Schmidt is murdered by Gesche Gottfried.
- 1847 — Samuel Herbert Dougal is born.
- 1894 — Louis Juncken is murdered by Martha Needle.
- 1931 — William A. Renfroe died.
- 1947 — Robert Liberty is born.
- 1950 — Milton Johnson is born.
- 1966 — Cletus Reese died.
- 1974 — Erno Soto is apprehended.
- 1979 — Koos Hertogs's victim, Tialda Visser, is found.
- 1981 — Donna Payant is murdered by Lemuel Smith.
- 1982 — Lorraine Borowski is murdered by the "Ripper Crew".
- 1985 — Christine Gallegos is allegedly murdered by Paul Rhoades (suspected victim).
- 1990 — Donna Perry's victim, Kathleen A. Brisbois, is found.
- 1990 — Kathy Brisbois is allegedly murdered by Robert Lee Yates (suspected victim).
- 1992 — Aileen Wuornos is sentenced to Death for the second time.
- 2009 — Mahin Qadiri is apprehended.
- 2014 — Susumu Nakayama died.
- 2017 — Ian Brady died.
- 2020 — Cleber de Souza Carvalho is apprehended.
- 2021 — Andrés Mendoza is apprehended.
- 2021 — Leslie Lizet Basilio is murdered by Keith Gibson.
- 2023 — José Quevedo is apprehended.