| Knock Knock | |
| Type: | studio |
| Artist: | Smog |
| Cover: | Knock Knock.jpg |
| Label: | Drag City |
| Producer: | Jim O'Rourke |
| Prev Title: | Red Apple Falls |
| Prev Year: | 1997 |
| Next Title: | The Manta Rays of Time |
| Next Year: | 2000 |
Knock Knock is the seventh studio album by Bill Callahan, released under his Smog alias. It was originally released through Drag City in January 1999. In Europe, it was released through Domino Recording Company.
Heather Phares of AllMusic gave the album 4.5 out of 5 stars, calling it "Bill Callahan's subtlest collection of songs yet." She added, "It's a moving album on many levels; not only do the songs have Smog's usual emotional intimacy, their subjects move away from difficult, claustrophobic situations toward maturity and acceptance."
Michele Romero of Entertainment Weekly gave the album a grade of B+, saying, "The energy jolt serves him well, making the delicate broken spirit of his lyrics cathartic rather than depressing."
NME listed it as the 10th best album of 1999.[1] Steve Jelbert of The Independent named it the best pop album of 1999.[2]