Larry William Eyler (December 21, 1952 – March 6, 1994), also called the Interstate Killer and the Highway Killer, was an American serial killer who murdered a minimum of twenty-one teenage boys and young men in the Midwest between 1982 and 1984. His victims were all discovered in locations close to or accessible via the Interstate Highway System in the states of Indiana and Illinois.

Eyler was convicted and sentenced to death by lethal injection for the 1984 kidnapping and murder of 16-year-old Daniel Bridges in Rogers Park, Illinois. While on death row he voluntarily confessed to the 1982 murder of 23-year-old Steven Agan, offering to also confess to his culpability in twenty further unsolved homicides if the state of Illinois would commute his sentence to life imprisonment without parole.

Eyler died of AIDS-related complications in 1994 while incarcerated on death row. Shortly before his death, he confessed to the murders of twenty further young men and boys to his defense attorney Kathleen Zellner, although he denied being physically responsible for the actual murder of Bridges, which he insisted had been committed by an alleged accomplice in five of his homicides, Robert David Little. With her client's consent, Zellner posthumously released Eyler's confession following the formal announcement of his death.