An Omelet or omelet is a preparation of beaten egg cooked with butter or oil in a frying pan, often folded around a filling. Gourmet cook Julia Child famously described an omelet as soft-cooked scrambled eggs wrapped in an envelope of firmly-cooked scrambled eggs. Many variations exist.

• Spanish Tortilla de Patatas (European Spanish for "potato omelet") is a characteristic thick omelet stuffed with fried potatoes and fine cut onion, and fried using olive oil. See also tortilla. In Britain this is called a Spanish omelet, and may include cheese or cooked diced ham.
• A Western omelet, also known as a Denver omelet, is an omelet filled with diced ham, onions, and green bell peppers. Often served in the midwestern United States and sometimes has a topping of cheese and a sidedish of hashbrowns or fried potatoes.
• In the United States, a Spanish omelet is an omelet served with an often spicy sauce of tomatoes, onions, and bell peppers.
• Frittata is a kind of open-faced Italian omelet that can contain cheese, vegetables, or even leftover pasta. Frittate are cooked slowly. Most often, they are cooked on the stovetop on low heat until the eggs are set, then run under the broiler, but they can also be baked. Except for the cooking fat, all ingredients are fully mixed with the eggs before cooking starts.
• In Japan, omelet (pronounced omuretsu) can mean a western omelet but also Omuraisu (from the English words "omelet" and "rice"). It is a fried ketchup-flavored rice sandwiched with a thinly spread beaten egg or covered with a plain egg omelet. Omu-soba is an omelet with yakisoba as its filling. Okonomiyaki is a Japanese pancake which is often compared to an omelet.
• A Chinese omelet can be an Oyster Omelet.
• A Thai omelet can be a Kai Yat Sai.