Theodore "Ted" Olson, who served as U.S. solicitor general under President George W. Bush, died on Wednesday, according to his longtime firm, Gibson Dunn & Crutcher. He was 84.

Over the course of a legal career that spanned nearly six decades, Olson became one of the most prominent Supreme Court lawyers of his generation, a conservative legal icon of the Bush years who later embraced gay rights, championed undocumented "Dreamers" and criticized President-elect Donald Trump. From Bush v. Gore to Citizens United v. FEC, Olson was at the center of some of the biggest conservative legal victories of the 21st Century, even as he advocated more liberal legal causes toward the back end of his years in practice.

"Ted Olson was an extraordinary public servant, a frequent and gifted Supreme Court advocate (he prevailed over me in the one case we argued against each other), and a good friend," Chief Justice John Roberts Jr. said in a statement. "I will miss him."

Justice Sonia Sotomayor called Olson a "champion of the legal profession."

Justice Elena Kagan, who also occupied the position of U.S. solicitor general, said Olson gave her valuable advice about "how to do the job." Kagan's first oral argument as solicitor general was against Olson in the Citizens United campaign finance case, in which the latter ultimately prevailed.

"He was an A-plus-plus lawyer, and an A-plus-plus man," Kagan said. "The whole OSG [Office of Solicitor General] community, and of course the Supreme Court will greatly miss him."

Justice Brett Kavanaugh called Olson a "model lawyer and a legendary public servant" and said he will "greatly miss his wisdom and humor."

Olson had long been one of Gibson Dunn's most well-known attorneys, having joined in 1965 and gone on to found its prominent appellate and constitutional law practice group.

He served two stints in government. The first was from 1981 to to 1984 as assistant attorney general in the Department of Justice's Office of Legal Counsel during the administration of President Ronald Reagan.

Two decades later, he served as solicitor general under Bush from 2001 to 2004. Over the course of his long career as one of the nation's most prominent Supreme Court lawyers, Olson argued 65 cases before the justices.

Arguably his most famous came while in private practice in the 2000 case Bush v. Gore, during which he argued on behalf of the Republican presidential nominee that the Supreme Court should declare the Florida recount ordered by the state supreme court unlawful. The justices ruled in Bush's favor in a 5-4 decision that effectively decided the 2000 presidential contest for Bush.

Despite being known as a conservative lawyer, Olson notably teamed up with his opposing counsel in the Bush case, David Boies, to challenge a California amendment against same-sex marriage. During President Donald Trump's first administration, Olson rejected an overture to join Trump's legal team during the investigation of ex-special counsel Robert Mueller.

"Ted Olson was a giant in the law, and a giant in life," Boies said in a statement to the National Law Journal. "He left the law, our country, and each of us better than he found us. Few people are a hero to those that know them well. Ted was a hero to those who knew him best."

Olson successfully challenged the Trump administraiton's rescission of the Deferred Action for Childhood Arrivals, or DACA, program giving immigration relief to thousands of noncitizens who came to the country as children. And as Trump's allies continued to fight President Joe Biden's victory in the days after the 2020 election, Olson told an audience at a Federalist Society event that the election was "over" and that "we do have a new president."

He later told the National Law Journal that the Senate has enough evidence to convict Trump for inciting deadly insurrection.

Tragedy struck Olson's life on his 61st birthday on Sept. 11, 2001, when his wife Barbara K. Olson died during the 9/11 terrorist attack on the Pentagon. Barbara had been a passenger on Los Angeles-bound American Airlines Flight 77 out of Dulles International Airport when it was hijacked by terrorists and flown into the building. She called her husband from the plane in a panic during the highjacking as Olson was at his office at the Department of Justice in Washington.

Having been confirmed as President Bush's solicitor general only months before in a politically charged Senate process, Olson was just weeks from the start of the upcoming October 2001 Supreme Court term when the attacks occurred. Grief-stricken, Olson carried out his legal work and would personally argue before the Supreme Court less than a month later, returning several more times over the ensuing months to represent the Bush administration before the nation's top legal tribunal.

"Ted entered the SG’s office as a legal giant and left as a truly historic solicitor general," said Latham & Watkins' Gregory Garre, who worked alongside Olson in the office at the time. "Few SGs had a more successful record before the court, and argued more momentous cases before the court, than Ted. Ted also led the SG’s office at a time of peril for the country, and great personal loss for him, in the wake of the 9/11 attacks. Ted’s leadership during this time was inspiring for all of us in the SG’s office.... Ted will be greatly missed."

In 2006, Olson, then soon to be remarried, told the Legal Times' Tony Mauro that it was important to "move on" from the tragedy.

"It’s important to understand that while I suffered a great loss, everyone else experiences great loss at some time too," he said. "It’s important for each of us to accept what happened and move on and do everything possible to go on with leading a productive life.”