- Lara Croft: In Tomb Raider: Underworld, Lara once again assumes the position of protagonist. In this game, Lara continues her quest to find Avalon and save her mother. She is voiced once again by Keeley Hawes, who voiced her in Tomb Raider: Legend and Tomb Raider: Anniversary.
- Winston Smith: Lara's butler, who has appeared in previous games, makes an appearance in Tomb Raider: Underworld and helps Lara convince Zip that she is not the doppelgänger. He is voiced by Alan Shearman.
- Zip: Zip returns, reprising his role from Tomb Raider Chronicles and Tomb Raider: Legend as Lara's tech-savvy friend. He almost shoots Lara at the beginning of the game, mistaking her for the doppelgänger. He is once again voiced by Alex Désert.
- Alister Fletcher: Alister also returns, reprising his role from Tomb Raider: Legend as Lara's book-smart friend. His role is smaller in this game than in Tomb Raider: Legend as he is killed by the doppelgänger. He is once again voiced by Greg Ellis.
- Amanda Evert: Another person to return in this game is Amanda, reprising her role as an antagonist from Tomb Raider: Legend. Amanda is still set on finding Avalon, and is also an enemy of Natla. Kath Soucie returned to provide Amanda's voice.
- Jacqueline Natla: Natla returns, reprising her role from the original Tomb Raider and its remake, Tomb Raider: Anniversary. In this game, Natla is the one who creates and unleashes the doppelgänger. She is searching for Avalon so she can unleash the Midgard Serpent Jörmungandr, who will bring about Ragnarök, an apocalyptic event that with usher in the Seventh Age. Natla is voiced by Grey DeLisle, who also voiced her in Tomb Raider: Anniversary.
- Doppelgänger: The doppelgänger is a complete reconstruction of Lara that was created by Natla for her to use for evil ends. The doppelgänger blows up Croft Manor and is also the person that murders Alister. She is later defeated by Amanda, who uses her Wraith Stone to best her. However, the Xbox 360 downloadable content Lara's Shadow has revealed that she is in fact alive, and is used by Lara to ultimately kill Natla, who has survived the fall into the eitr.
- Amelia Croft: Lara's mother, Amelia Croft, appears briefly and has been turned into a "thrall", a deceased individual whose corpse is reanimated by the substance eitr. As the mindless thrall approaches, Lara shoots her, whispering, "No, no, no, you're not my mother. My mother died a long time ago".
Read more about this topic: Tomb Raider Characters