The Anakim are a race of large giants found in Biblical lore, distinct from the more infamous Nephilim and often stated to be the direct offspring of Anak, the ruler who gave them their name (who himself is part of the Rephaite, another race of demi-giants described in some texts).
They were feared by the early Hebrews for their great size and barbaric nature, with Joshua managing to drive many of them away with time, but some would retire to distant lands and form alliances with the enemies of God.
The most famous giant in Biblical lore, Goliath, was sometimes referred to as a member of the Anakim, though he was usually depicted as a fairly "small" giant.
However, the Anakim themselves were said to gradually get smaller as time went by, due to losing influence and larger members of their kind being driven off or dying.