Robert Downey Jr.
While on parole from a previous drug-related arrest, the Ally McBeal guest star was taken into custody on suspicion of being under the influence on Apr. 24, 2001. At the time, a police officer found the actor walking barefoot through Culver City, Calif. Downey -- who had traces of cocaine in his system -- pleaded no contest to his initial arrest charges and was ordered to complete a drug rehabilitation program. He was also given three years probation.