FRIDAY, OCT. 30

Halloween Extravaganza: The “3rd on Third” free Bayview bash includes live music, a haunted house, pumpkin carving, costume contests, mask making and prizes. [5 to 8 p.m., Mendell Plaza, Third Street and Oaklale Avenue, S.F.]

BOO!: DJ acts Flosstradamus, Oliver Heldens, The Magician, Ghastly, Shaun Frank, Alison Wonderland and Dr. Fresch appear in the first of a two-day event. [5 p.m., Bill Graham Civic, 99 Grove St., S.F.]

KORN: The Grammy Award-winning hard rock innovators are topping off 20th anniversary celebrations by performing their debut album “KORN” in its entirety; Suicide Silence and Islander open the show. [7:30 p.m., Fox Theater, 1807 Telegraph Ave., Oakland]

Cassy: The vocalist-turned-star DJ known for her long-form minimal techno DJ chops, headlines a show with funky Polish house duo Catz ‘n Dogz, the British Adana Twins, and the return of former San Francisco institution Nikola Baytala. [9:30 p.m., Public Works, 161 Erie St., S.F.]

John Keene: The author discusses “Counternarratives,” his collection of stories and novellas that draw upon memoirs, newspaper accounts, detective stories, interrogation transcripts and speculative fiction. [7:30 p.m., Green Apple Books, 1231 9th Ave., S.F.]

Tavi Gevinson: The 19-year-old writer and editor of “Rookie Yearbook #4!,” who founded Rookiemag.com, an influential website created by and for young women, appears. [7 p.m., Books Inc. Opera Plaza, 601 Van Ness Ave., S.F.]

Aquarium of the Bay: For Halloween, the attraction offers “creepy creatures and freaky fish” and 50 percent off general admission for kids 12 and under who come in costume. [10 a.m. to 7 p.m., Pier 39, 2 Beach St., S.F.]

SATURDAY, OCT. 31

Grimes: The award-winning Canadian record producer and synth pop artist brings her “Rhinestone Cowgirls” tour to town. [9 p.m., Fillmore, 1805 Geary Blvd., S.F.]

Greensky Bluegrass: The progressive bluegrass/jam band headlnes, promoting its latest album “If Sorrows Swim”; Tumbleweed Wanderers open. [7:30 p.m., Fox Theater, 1807 Telegraph Ave., Oakland]

Target Beauty U; The retailer and cosmetics manufacturers host a seasonal session, “Wicked Makeup Transformations: Create the Halloween Look Makeover.” [11 a.m. to 3 p.m., Target stores at Metreon, 789 Mission St., S.F.; Serra Shopping Center, 5001 Junipero Serra Blvd., Colma; Fashion Island, 2220 Bridgepointe Parkway, San Mateo]

Boograss-Hillbilly Halloween: The costume party and acoustic concert features Front Country, One Grass Two Grass and Rusty Stringfield. [9 p.m., Slim’s, 333 11th St., S.F.]

BOO!: DJ acts Nicky Romero, Seven Lions, Will Sparks, Snails, Kennedy Jones, DallasK and 4B appear in the second of a two-day event. [5 p.m., Bill Graham Civic, 99 Grove St., S.F.]

New Esterhazy Quartet: The chamber group’s program “Padre, Guida, ed Amico!” honors the decades-long dialogue between Mozart and Haydn. [4 p.m., St. Mark’s Lutheran Church, 1111 O’Farrell St., S.F.]

Arcane: Company C Contemporary Ballet premieres its one-act dance celebrating the spirit and spirits of Halloween. [1 and 7 p.m., Cowell Theater, Fort Mason, Marina Boulevard and Buchanan Street, S.F.]