Tyrannosaurus Rex

 (abbreviated to T.rex) is a dinosaur appearing in a multitude of Tomb Raider games.

Tactics
The T.rex has many ways to hurt or kill Lara, so it's really a death-wish to stay near it. The T.rexes in the first three games can damage Lara by touch and possess a bite attack that will instantly kill Lara if it makes contact, resulting in a death animation. The T.rex in Tomb Raider: Anniversary has multiple bite attacks and will use a tail whip attack if Lara is right behind it. It can knock Lara to the ground by touch, diminishing some of Lara's health. It will charge when it gets enraged from repeated shooting.

Tomb Raider / Tomb Raider: Anniversary
There's a cave in the valley where you can take shelter and shoot it from there. It's the best way to kill it. You can also use the shotgun from close range to make quick work of it. Another way is to equip the pistols as soon as possible, and back flip and shoot it until it dies.

This battle was reincarnated in Tomb Raider: Anniversary, the re-imagining of the classic original Tomb Raider game. However, the tactics are different this time, especially with the introduction of the adrenaline dodge. Before the fight, there will be a quick-time event so follow the button presses. Then the real battle begins. You must endlessly shoot it. Once it gets enraged, stop shooting but keep your guns drawn and try go in front of one of the spiked structures. When it attempts to attack you by charging, dodge to the left or right, and when the two red reticules overlap, immediately shoot! You can say that your adrenaline dodge attack was successful if the T.rex hits the spiked structure. This takes away one-third of the dinosaur's health meter. This means that it takes three spiked structures to defeat the T.rex. While making the T.rex run into the mountain wall or anything other than those spiked structures still does some damage, it doesn't lose anywhere near as much health. Once the T.rex's health reaches zero, another quick-time event ensues so just follow the button presses to finally take down the dinosaur.

Tomb Raider II
There are two in the same area! Though the second one only appears when you leave the small hole containing the third secret. To safely kill them, shoot while staying in the little hole where the secret was until they go down. Another strategy is to kill the first T.rex before spawning the second one. These T.rexes have around the same amount of health as the one from the first game.

Tomb Raider III
Right after you grab the key that was in its nest, it appears. Run as fast as you can to the small cave with a lever (it is right at the side of the slope that you used to get down) to kill it from a distance. Staying in the deep water is also a safe way to kill it. Unlike the T.rexes in the previous two games, this one has an immense amount of health in comparison.

Lara Croft: Relic Run
A T.rex appears as a boss of Cambodia's Jungle Temple. Easiest way to kill it, is with maxed-out Crossbow. If you are fast enough with the clicking, you can take out T.rex with two encounters (gets tougher after every kill).

Tomb Raider reloaded
T.rex appears as a boss of stage 50 of Chapter 4 - The Lost Valley. The mechanics are slightly similar to the one in Tomb Raider: Anniversary where, he can be lured into spiked walls for more damage.

Tomb Raider

 * Lost Valley (1)

Tomb Raider II

 * The Great Wall (2)

Tomb Raider III

 * Crash Site (1)

Tomb Raider II: Golden Mask

 * Nightmare in Vegas (2)

Tomb Raider: Anniversary

 * Peru - The Lost Valley (1)

Lara Croft: Relic Run

 * Jungle Temple (2)

Tomb Raider Reloaded

 * The Lost Valley, Stage 50 (1)

Trivia

 * The T.rex in Tomb Raider: Anniversary, as the commentary states, is probably much larger than a real Tyrannosaurus Rex would be.
 * There's a T.rex trophy inside Lara's treasure room in Tomb Raider III.
 * Tomb Raider II, Tomb Raider III, and Lara Croft: Relic Run T.rexes have 3 digits on each hand, whereas the one in Tomb Raider and Tomb Raider: Anniversary have the correct number of digits; that being 2. It can be pretended that the giant dinosaurs we see in Tomb raider 2-3 aren't actually T.Rexes at all, and instead one of the carnosaurs such as Giganotosaurus, Allosaurus, Carcharodontosaurus, or Saurophoganax. However, the TR3 case confirms that the large, 3 fingered dinosaur in Crash Site is indeed a T.rex.
 * The T.rex in Tomb Raider III will sometimes respond to the flare that's dropped on the ground by the player. This is most likely a reference to Jurassic Park/World.
 * The T.rex in the first Tomb Raider will completely ignore any Raptors that are present whereas the one in Tomb Raider III will decide to fight and kill any Raptors that are near it.
 * In TR1, when the T.rex dies, its corpse is still tangible, meaning the player can't run through the body. In TR2 and TR3 however, the T.rexes' body become intangible when they are killed, so the player can run through them.

Appearances

 * Tomb Raider: Featuring Lara Croft (First appearance)
 * Tomb Raider II: Starring Lara Croft
 * Tomb Raider III: Adventures of Lara Croft
 * Tomb Raider II: Golden Mask
 * Tomb Raider: Anniversary
 * Lara Croft: Relic Run
 * Tomb Raider Reloaded