A senior administration official said both men are "notorious cybercriminals who have been responsible for ... havoc in the international financial system, including against American companies."
Evgeniy Bogachev and Aleksey Belan are not being connected to alleged Russian efforts to interfere with U.S. election processes, according to the Treasury Department, although sanctions against them were announced at the same time as sanctions against other Russian individuals and entities allegedly involved in efforts to interfere with U.S. election-related institutions.
"As all of these actions make clear, we will not tolerate the abuse of our systems, including our election systems, by foreign actors," the senior administration official said of the sanctions in a call to reporters.
Here is what is known about the two hackers:
Evgeniy Mikhaylovich Bogachev
The 33-year-old is a Russian national whose involvement in online theft schemes has been under investigation by the FBI since 2009.
He usually shaves his head and "is known to enjoy boating and may travel to locations along the Black Sea in his boat," according to the FBI's most wanted poster for him.
Bogachev has used at least five online aliases, two of which — lucky12345 and slavik — were listed by the FBI.
He is wanted for "alleged involvement in a wide-ranging racketeering enterprise and scheme that installed, without authorization, malicious software known as Zeus on victims' computers," the FBI poster states.
The malicious software was used to steal passwords, bank account information and other personal identification numbers, which were then used to steal money from victims' bank accounts, according to the FBI.
An updated version of that software was believed to be responsible for more than a million computer infections, which the FBI connected to financial losses of more than $100 million.
A criminal complaint was issued in Nebraska after the second indictment that connected his legal name to the earlier indictment.
His poster says the FBI is offering a reward of up to $3 million for information leading to his arrest or conviction.
Aleksey Alekseyevich Belan
The 29-year-old hacker is a Latvian with Russian citizenship and a Russian passport, according to the FBI's poster for him.
The FBI lists six other variations of his name plus five online aliases, and the Treasury Department lists an additional five online aliases.
He is wanted for allegedly infiltrating "the computer networks of three major United States—based e-commerce companies in Nevada and California. He is alleged to have stolen their user databases, which he then exported and made readily accessible on his server" in 2012 to early 2013, the FBI says. "Belan allegedly stole the user data and the encrypted passwords of millions of accounts and then negotiated the sales of the databases."
Two federal arrest warrants for Belan have been issued, and the FBI is offering a reward of up to $100,000 for information leading to this arrest.
Editor's note: This article has been amended to clarify that Bogachev and Belan are not being connected to efforts to interfere with election processes. This clarification was made when ABC News received additional information from the Treasury Department about the basis for the sanctions against the two men.