Tomb Raider - Underworld is the last tomb raider game also known as tomb raider 8. As a series their is coming a new tomb raider always.

Eidos chief Ian Livingstone’s teased the next Tomb Raider for the first time, saying the game is to “reinvigorate” the IP after a lukewarm Underworld reception.

“The next Tomb Raider, I think, will surprise a lot of people and reinvigorate the franchise,” he said.
“There are some remarkable things we’re doing in the next Tomb Raider to make you say, ‘Oh Lara, I love you so much!’”

We’re willing to bet you a huge amount of money it doesn’t make us say that, Ian.

There is a rumor that the next tomb raider is being developed by Crystal Dynamics & Buzz Monkey both. In their website Buzz Monkey stated that "We are currently hard at work on our next smash success." Does that mean another Tomb Raider? The firm Buzz Monkey developed the PS2, PS3 and Wii for Underworld, and worked on the previous two Tomb Raiders as well.
Underworld’s senior environmentalist, Caleb Strauss, has listed an “Unnanounced Project” on his resume, stating his involvement includes “pre-production development, 3D world environment modeling, documentation, contribution to art pipeline and workflow, and mentoring.”

There’s no other detail as yet. But we expect to know more soon, hopefully.

Tomb Raider 3 movie also coming. Rumour that Angelina Jolie will not appear to reprise her role. Tomb Raider 3 will be based on younger Lara Croft and Megan Fox (Actress of Transformers) will act as Lara Croft.