Giants, according to the Bible, lived both before and after Noah's flood! Those who possessed larger than normal bodies, before the deluge, were known as the Nephilim (Genesis 6:4). Their name means a bully or a tyrant (Strong's Concordance #H5303). This group of belligerent, evil obsessed giants, like the rest of humanity, perished when God caused water to cover the entire earth.
The first mention of giants after the flood is in the book of Numbers. Ten of the twelve men Moses sent to spy out the Promised Land reported seeing huge people known as the children of Anak (the Anakim). It was Israel's faithlessness, and fear of the giants in the land of milk and honey, that caused them to be punished by wandering the wilderness for forty years (Numbers 13:32 - 33, 14).
The Israelites, while wandering the wilderness, encountered a second group or race of giants led by Og, king of Bashan (Deuteronomy 3:11). The king was an enormous man, sleeping in a bed 9 cubits long (roughly 13 1/2 feet or 4.1 meters) by 4 cubits wide (6 feet or 1.8 meters)! For comparison purposes, the most common large mattress in the United States is 6.6 feet long (2 meters) by 6.3 feet wide (1.9 meters).
The third mention of gigantic people in the Bible is the well-known story of a young king David fighting Goliath the Philistine. Goliath was one of several tall and strong Philistines. He was six cubits and a span tall (1Samuel 17:4). If we use a conservative length of a cubit (18 inches), Goliath was at least 9 feet 3 inches tall (2.82 meters) and likely bigger!
Goliath the giant could wear a protective battle coat weighing more than 80 pounds U.S. while also carrying a massive 26-foot (7.9 meters) spear. The head of his spear was stated to weigh an amazing 17 pounds U.S. (7.7 kilograms)! He was also one of at least two giants in the same family.
Amazingly, during King David's life, he and his men encountered several giants other than Goliath. One of them was named Ishbibenob, whom David killed with the help of Abishai (2Samuel 21:16). Another of the giants was Saph, who was killed by one of David's men named Sibbecai during a battle between the Israelites and Philistines at Gob (verse 18).
A third man of giant stature, who apparently liked to fight and had six fingers on each hand and six toes on each foot, was killed by Jonathan. He was the son of one of David's brothers (2Samuel 21:20). The Bible credits all these victories to David or one of his men (verse 22).
In conclusion, the Bible records at least three groups or races of people who produced giants after the flood. They were the Anakim (children of Anak), the people of Bashan, and the Philistines (Rephaim).