Bats are the first enemy that you encounter in the game and are one of the easiest to defeat. However, if you chose to try and ignore them, they will keep nipping away at Lara's health. Sometimes you may hear them before you see them as you'll hear the flapping of their wings.
FIRST APPEARANCE: Caves
These are the first enemy that are introduced in Tomb Raider, seen in the cutscene where Lara and her guide, Carlos, are trekking to the location of the Tomb of Qualopec. They are quick and hunt in packs, so there are times where Lara will be outnumbered and cornered. However, it can take one good shot from the shotgun to take them.
FIRST APPEARANCE: Caves
The velociraptors are one creature that you probably didn't expect to see in a game set in the modern era but they are perfectly placed in an ancient and almost prehistoric like setting. They are quick and will claw at Lara if they get too close. The shotgun is good against these too as one well timed shot is enough to kill it, if you are lucky.
FIRST APPEARANCE: Lost Valley
Mummified Crawling Atlantean
These are Egypt's version of the Atlanteans that Lara will later encounter. They are only seen (to fight) in two levels: 'City of Khamoon' and 'Obelisk of Khamoon'. They do not possess any weapons; instead they jump, bite and claw at Lara to damage her. Qualopec has two of these guarding him and his piece of the Scion in his tomb.
FIRST APPEARANCE: City of Khamoon
These nasty guys often appear in a place where the walkway is narrow and is very high off the ground. They can push Lara off the edge and to her death. If you have the Uzis, they are useful against the flying Atlanteans, especially to keep them at bay.
FIRST APPEARANCE: Sanctuary of the Scion
A centaur is quick on their feet but with a wide turning circle, so the best tactic against these creatures is to flip side to side to dodge their fireball attacks, keeping a slight distance for you to keep an eye on their line of fire and dodge accordingly.
FIRST APPEARANCE: Tomb of Tihocan
The largest enemy that Lara will encounter, it's no wonder that it takes a while to kill it. There is plenty of Uzi ammo about so it is advisable to pull out them Uzis and get firing. The other pitfall to fighting the abomination is the platform that Lara is standing on - not only does it feel like there isn't enough space between you and the enemy, but one false move and Lara is over the edge.
FIRST APPEARANCE: The Great Pyramid