Ernst Stavro Blofeld is the main antagonist of Spectre. He is James Bond's foster brother and archenemy, being responsible for the latter's recent losses ever since the James Bond series rebooted with 2006's Casino Royale; thus he is the overall main antagonist of the reboot series.
He is portrayed by Christoph Waltz, who also portrayed Hans Landa in Inglorious Basterds.
Franz Oberhauser was born in the 1960s as the son of an Austrian couple named Hannes Oberhauser and Trudi Blofeld-Oberhauser, and his family was friendly with James Bond's parents. When Bond's parents died in a climbing accident, James was adopted by Hannes, who instructed Franz to treat James like a brother. However, Franz grew to hate and envy James, believing his father loved Bond more than him. At one point, Hannes and Franz were involved in an avalanche in which both of them apparently died. However, in truth, Franz killed his father out of jealousy and staged his own death while adopting his mother's maiden name.
As the years went by while James grew up to become one of MI6's best agents in the field, Blofeld went on to form a mysterious but notorious criminal organization known as SPECTRE. Under Blofeld's leadership, the organization became an extremely powerful group while retaining its complete anonymity to the world, staging many terrorist attacks throughout the years. Through the shadows of several SPECTRE's agents (such as Le Chiffre, Vesper Lynd, Mr. White, Dominic Greene, and Raoul Silva) and Quantum (which happens to be a subsidiary of SPECTRE), Blofeld had secretly caused several personal tragedies to James while continuing on executing more attacks around the world, gaining more power with each move he made. Even after the deaths of Le Chiffre, Lynd, Greene, and Silva, as well as the dismantling of Quantum, Blofeld maintained SPECTRE's complete anonymity to the public as planned to invoke more pain on Bond for his own amusement.
Blofeld first appears briefly at the funeral of Marco Sciarra (one of SPECTRE's assassins) and Bond spots him, though without recognizing his face. Blofeld later appears at the SPECTRE meeting in Rome, where, after allowing Bond a short, brutal insight of SPECTRE, he exposes the latter, who was eavesdropping on the meeting. Bond makes his escape after a car chase with another SPECTRE assassin, Mr. Hinx.
Bond finds Mr. White, who had grown disillusioned with SPECTRE once it began dealing in human trafficking of women and children. White revealed that Blofeld had poisoned him with thallium, and that he had only days to live. White asks bond to save his daughter, Dr. Madeleine Swann, and then commits suicide. Bond and Swann head to a Moroccan hotel called L'Americain, where they find coordinates to Blofeld's main facility in the Sahara desert. While traveling there, the pair once more encounters Hinx and after a brutal fight they are able to kill the assassin. Bond and Swann arrive at the facility, but Blofeld has awaited their arrival. He reveals that he plans to take control of the world's intelligence systems through the Nine Eyes program developed by Max Denbigh (the head of the Joint Intelligence Services and one of SPECTRE's agents) and that he had arranged the '00 section to be shut down, using Denbigh's influence. Blofeld also reveals that he and SPECTRE were secretly behind the actions of Le Chiffre, Lynd, White, Greene, Silva, and Quantum. He then plays surveillance footage of Mr. White's suicide, driving a spike between Bond's and Swann's relationship. Blofeld's henchmen knock Bond unconscious.
Upon awakening, Bond finds himself strapped to a surgical chair. Blofeld attempts to lobotomize Bond, but Swann, who has been given an exploding watch from Q Branch by Bond, uses the device to destroy the machine and seemingly kill Blofeld. Bond and Swann escape the facility before it blows up, killing the majority of Blofeld's men in the process.
Since the Moroccan base was just one node in a wider network, Bond and Swann head back to London, where he conspires with M, Q, Bill Tanner, and Moneypenny to arrest Denbigh and stop the Nine Eyes program from going online. However, on the way, Bond is captured by several of SPECTRE's agents and taken to the derelict ruins of the old MI6 headquarters. Bond manages to kill the SPECTRE agents, and ventures inside the ruins, eventually finding Blofeld, who survived the explosion but was left with a facial scar and blinded eye. Bond tries to shoot Blofeld, only to have his bullets held at bay by the bullet-proof glass placed between them. Blofeld then reveals that he has kidnapped Swann and left her somewhere in the building, which is elaborately rigged with explosives. Blofeld gives Bond two options: either die in the explosions while trying to save Swann, or to save himself but leave Swann to die. Blofeld then enters a helicopter, which hovers over the Thames to allow Blofeld to watch Bond die. However, Bond and Swann escape seconds before the building explodes. In the meantime, Q manages to shut down Nine Eyes while M manages to finish off Denbigh, who ends up falling to his death several stories below.
Believing Bond to be dead, Blofeld, along with his personal assistant and pilot, are about to escape, unaware that Bond and Swann are pursuing them in a speedboat. After a climactic chase, Bond manages to shoot down the helicopter's fuel tanks, sending it crashing onto Westminster Bridge, severely wounding Blofeld's leg and killing both his pilot and personal assistant. Blofeld tries to crawl away from the wreckage, but is held at gunpoint by an arriving Bond. Realizing that he can't escape alive and is now at 007's mercy, Blofeld tells Bond to kill him, but Bond refuses by unloading his gun, fully aware that killing him out of revenge would sink Bond to Blofeld's level. Blofeld is then arrested and imprisoned by the British Secret Service for crimes against humanity.