Sizzler USA Restaurants, Inc., doing business as Sizzler, is a United States–based restaurant chain with headquarters in Mission Viejo, California, with locations mainly in California, plus some in the nearby states of Nevada, New Mexico, Idaho, Utah, and Oregon, as well as Puerto Rico. It is known for steak, seafood, and salad bar items.

Since 2023, Sizzler restaurants outside of the United States are owned by Thailand-based Minor International and are not related to the American firm.

In September 2020, Sizzler USA filed for Chapter 11 bankruptcy due to the COVID-19 pandemic hurting sales. The bankruptcy filing does not affect the similarly named Minor International affiliated restaurants that are located outside of the United States. Sizzler USA emerged from bankruptcy in January 2023.

The chain was founded in 1958 as Sizzler Family Steak House by Del and Helen Johnson in Culver City, California. At its peak, the chain was composed of more than 270 locations throughout the U.S. Most of Sizzler's U.S. locations are in the West.

In the late 1970s and early 1980s, Sizzler promoted steak and combination steak dinners with an optional salad bar. The restaurant wanted to give customers the feel of a full-service restaurant at a price slightly more than a fast food chain. To control costs, many restaurants had in-house meat cutters who would cut steaks and grind beef.

Into the early to mid-1980s, competition appeared: Ponderosa Steakhouse and Bonanza Steakhouse. After promotions, such as all-you-can-eat fried shrimp, the chain expanded its salad bar into a full buffet promoted as the "Buffet Court". Patrons began to use the buffet as a meal instead of an add-on to an entree. In response, Sizzler lowered the quality in other menu areas. Customers took notice, and Sizzler's reputation suffered.

Sizzler filed for Chapter 11 bankruptcy in 1996 ("to escape costly leases on unprofitable restaurants"), and closed over 130 of its locations. The company reemerged from Chapter 11 in 1997. During the late 1990s, new management upgraded the quality of food and increased prices. Twenty-one locations closed in 2001. Sizzler began an image makeover around 2002. A new restaurant concept was created, featuring a lighter and more open dining room. The changes were accompanied by a new menu. In an effort to return to its roots, Sizzler emphasized steaks, seafood, and the salad bar. While the all-you-can-eat buffet was phased out in some locations, it remained in many others.

In the 1990s, Sizzler ran upscale locations with the Buffalo Ranch Steakhouse brand.