Given that it shares the Italian root for "to melt" with fondue, it's not surprising that fontina is one of the key cheeses used in fondue dipping blends. Younger varieties of this cow's milk cheese are semisoft, with the milder taste and yielding texture that makes them preferable for melted-cheese dishes. Aged fontina makes for an aromatic "stinky" addition to the cheese tray. Depending on what you're making and your own preferences, other cheeses can be used to substitute for the Italian classic, either as cooking or table cheeses.
Swiss Family Fondue
Like fontina, Swiss Gruyère is a fondue favorite that comes from the Swiss Alps, rather than the Italian side of the border. Swiss Gruyère also works well in root vegetable gratins and in souffles. A hard cheese, Emmental features the large holes many of us associate with Swiss cheese. Emmental has a fruity, slighty acid taste. A third possible fontina alternative hailing from Switzerland, Appenzeller is popular in both young and aged forms. The non-aged form of Appenzeller has a creamy texture and mild taste, making it more similar to fontina than the aged version, known as "festive," which is cured with a peppery, wine-soaked brine.
The Italian Job
Bel Paese was created to approximate Alpine melting cheeses such as fontina. Traditionally, this semisoft Italian cheese is melted on such classic Italian dishes as pizza or focaccia, or paired with fruit as a table cheese; but its buttery, mild flavor make it a passable alternative to fontina. Provolone is a semihard cow's milk cheese from Italy's Po valley. Although it may be more familiar to you as a sliced component purchased from the deli counter, younger provolone has a softer, milk taste that makes it a possible alternative to fontina on the cheese tray.
The French Connection
Comté is a Gruyère variety that is made in France. Comté contributes subtle hints of the flowers and other plants the cows graze upon, as well as a buttery taste and meltable consistency. Another well-known melting cheese from France, Reblochon is semisoft and made from cow's milk. In France, it's often used as a partner with potatoes, especially in the national staple gratin known as a tartiflette, made with Reblochon, potatoes, pork fat and onions.
Edam, the small spherical cheese with the familiar waxy-red rind, comes from the town of Edam in northern Holland. Like many other fontina alternatives, Edam works as both a cooking and table cheese. It's ideal in warm sandwiches, such as grilled cheese or as a topping for hamburgers. If you're using it in place of fontina in fondue or gratin dishes, you may need to reduce how much salt you add. Some Edam varieties are saltier than other cheeses.