Anak was the ancestor of a group of very tall people called giants who lived in ancient Canaan.
When Israel first reached Canaan, the Anakim were well established in Hebron. Ten of the 12 spies Moses sent into Canaan were terrified by the size of the Anakim (Numbers 13:17–22; 31). Their fear led to a rebellion at Kadesh-barnea (Numbers 14:39–45; Deuteronomy 1:19–46). It also led to another 38 years of wandering. When the Israelites were finally ready to enter Canaan, God promised his help against the famed Anak giants (Deuteronomy 9:1–3).
The two spies who were not afraid of the Anakim were both involved in their defeat. Joshua defeated the Anakim living in Hebron, Debir, Anab, and all the region of Judah (Joshua 11:21–23). Those who survived were left only in the Philistine cities of Gaza, Gath, and Ashdod. The other spy, Caleb, was responsible for the defeat of the Anakim chiefs Sheshai, Ahiman, and Talmai at Hebron. Caleb’s nephew Othniel was the hero of Debir (Joshua 15:14–17).
Hebron had earlier been called Kiriath-arba for Anak’s father Arba. He was a great hero of the Anakim (Joshua 14:15; 21:11). The fact that the Anakim survived in the Philistine cities of Gaza, Gath, and Ashdod leads to the supposition that Goliath of Gath may have been a descendant of these giants (1 Samuel 17:4–7).