Ice/glaciers
Lakes are water bodies surrounded by land. Lakes have bowl-shaped depression in the earth that is filled with water. This depression is referred to as Lake Basins. There are many ways these basins can be formed.
Many basins are formed due to the movement of tectonic plates that changes the Earth's Crust. When the Crust breaks, deep cracks, called Faults, may form. These faults make the natural basins and when filled with a nearby stream of rainwater to form a Lake.
Second, Glaciers. This is common with lakes formed in the northern hemisphere. During the last ice age, most of the land in the Northern Hemisphere was covered with Glaciers. The huge masses of ice carved out great pits and scrubbed the land as they moved along slowly. When the glaciers melted, water filled those depressions, forming lakes.
Third, Volcanos. After a volcano becomes inactive, its crater may fill with rain or melted snow. Sometimes the top of a volcano is blown off or collapses during an eruption, leaving a depression called a caldera. It, too, may fill with rainwater and become a lake.
Fourth, Astroids. This may be the least common way of forming lakes on earth. Many asteroids burn up during their entry in the earth's atmosphere, nut some do complete the journey and end up landing on the surface. The asteroids hit earth at extreme speed and create basins which later get filled up by nearby streams or rainwater.