President Biden issued preemptive pardons Monday to former medical adviser Anthony Fauci, retired Gen. Mark A. Milley and members of the House Select Committee on Jan. 6 to guard against retribution by incoming President Donald Trump.

Mr. Biden said the pardoned persons did not do anything wrong, but he feared Mr. Trump would prosecute them in a personal vendetta.

“The issuance of these pardons should not be mistaken as an acknowledgment that any individual engaged in any wrongdoing, nor should acceptance be misconstrued as an admission of guilt for any offense,” Mr. Biden said in the waning hours of his term. “Our nation owes these public servants a debt of gratitude for their tireless commitment to our country.”

The pardons are extraordinary because they guard against potential proceedings instead of waiving penalties or the stain of a criminal record from people who’ve committed crimes or been sentenced.

The closest parallel is likely President Gerald Ford’s decision in 1974 to grant a “full, free, and absolute pardon” to former President Richard Nixon, fearing a trial over the Watergate scandal would sow division in the country.

Mr. Biden had mulled the pardons for weeks, citing Mr. Trump’s rants against “enemies from within” and a potential target list.

Dr. Fauci, who led infectious diseases research at the National Institutes of Health, advised Mr. Trump in the early days of the COVID-19 pandemic and led vaccine research. He was also a constant media presence who pushed for social and business restrictions to curb the spread of the virus, making him the target of ire for Mr. Trump and his allies as restrictions took a toll on normal life.

While governors and local officials ordered the actual shutdowns, Mr. Trump’s allies accused Dr. Fauci of funding dangerous work at a lab in Wuhan, China, that might have resulted in a leak of the coronavirus, though probes are inconclusive.

“During his tenure as my chief medical adviser, he helped the country tackle a once-in-a-century pandemic. The United States is safer and healthier because of him,” Mr. Biden said.

Sen. Rand Paul, Kentucky Republican, said Mr. Biden’s pardon of Dr. Fauci only underscored his belief that the doctor was responsible for the COVID-19 crisis.

The senator pledged to investigate the virus’s origins as chairman of the Senate Committee on Homeland Security and Governmental Affairs.

“If there was ever any doubt as to who bears responsibility for the COVID pandemic, Biden’s pardon of Fauci forever seals the deal,” Mr. Paul said. “Fauci’s pardon will only serve as an accelerant to pierce the veil of deception.”

Gen. Milley turned into a vocal critic of Mr. Trump at the end of the Republican’s first term, including his handling of 2020 protests over police actions and race and the events that led to the Jan. 6, 2021, U.S. Capitol attack.

Mr. Trump also vented at members of the House panel who investigated his attempts to overturn the 2020 election results and the Jan. 6 attack on the Capitol, saying they hid key evidence and came down hard on innocent people.

Mr. Biden said the committee was established to achieve accountability for a dark day in U.S. history.

“These are exceptional circumstances, and I cannot in good conscience do nothing. Baseless and politically motivated investigations wreak havoc on the lives, safety, and financial security of targeted individuals and their families,” Mr. Biden said. “Even when individuals have done nothing wrong — and in fact have done the right thing — and will ultimately be exonerated, the mere fact of being investigated or prosecuted can irreparably damage reputations and finances.”

The pardons unleashed bitter acrimony on Capitol Hill.

House Oversight Committee Chairman James Comer, Kentucky Republican, accused his counterpart, Democratic Rep. Jamie Raskin of Maryland, of “hypocrisy” and “consistent dishonesty” for downplaying Mr. Biden’s business deals and accepting a pardon after serving on the Jan. 6 panel.

“Jamie Raskin once claimed that ‘the seeking of pardons is a powerful demonstration of the consciousness of guilt, or at least the consciousness that you may be in trouble,’” Mr. Comer said. “It’s clear that the chickens have come home to roost for Jamie Raskin.”