Which actor played Sergeant Mike Dodds?

Andy Karl played Sergeant Mike Dodds on Law & Order: Special Victims Unit.

Karl's Mike Dodds was introduced in season 17 as a NYPD sergeant transferred to Manhattan's Special Victims Unit. He became Lieutenant Olivia Benson's second-in-command and arrived with significant law-enforcement experience. The character had served in Special Forces after enlisting following the September 11 attacks, and he had previously worked in Anti-Crime and at the 71st Precinct.

Mike Dodds was also the son of Deputy Chief William Dodds, played by Peter Gallagher. That family connection is the most common source of confusion in this question: Peter Gallagher played Mike's father, not Mike himself. The two characters also had contrasting views about Mike's career, with William initially treating the SVU assignment as a stepping stone.

Karl's tenure on the series ran from 2015 to 2016. Mike Dodds was shot during a hostage situation in “Heartfelt Passages,” later suffered a fatal stroke, and died after being taken off life support.