Giants are arguably the most well known as a big and huge monster, alongside Goblins and Unicorns. The name from Norse mythology for these beings is the Jötunn. They have stature that is typically up to 20 times that of a Human and immense strength.
Some say giants breath fire. Some giants have great magical powers. Size vary(yet always huge.) how big exactly they are depends on the mythology or who is telling the story. Common hieghts are 20 feet to 500 feet. Some stories say they are stupid while others say they are smart.