Cheetahs and leopards.
Starting Statistics: Size Small; Speed 50 ft.; AC +1 natural armor; Attack bite (1d4 plus trip), 2 claws (1d2); Ability Scores Str 12, Dex 21, Con 13, Int 2, Wis 12, Cha 6; Special Qualities low-light vision, scent.
4th-Level Advancement: Size Medium; Attack bite (1d6 plus trip), 2 claws (1d3); Ability Scores Str +4, Dex –2, Con +2; Special Qualities sprint.
Sprint (Ex): Once per hour, a cheetah can move at 10 times its normal speed (500 feet) when it makes a charge.
The cheetah is a swift and deadly predator capable of moving with incredible speed, allowing it to run down unsuspecting foes hundreds of feet away. The hunting cat avoids areas of dense and tangled undergrowth, but has great skill at lying in wait in tall grass.
An adult cheetah is 4-1/2 feet long and weighs 140 pounds.