A 1-year-old child was killed when a truck being driven by his grandfather ran the boy over at a Roma camp at Diavata, just outside Thessaloniki.
The 51-year-old man was charged with manslaughter over the incident, which occurred last week but was only reported on Wednesday.
He was also charged with leaving the scene of the accident.
The man was apparently unaware the child was behind his vehicle while he was reversing.
In a separate incident, two men, aged 34 and 42, lost their lives after being run over, also by a truck, on Wednesday.
The men, both truck drivers, had parked their vehicles one behind the other at a rest stop area on the new Athens-Corinth highway near Derveni.
For as yet unknown reasons, one of the trucks began to roll and crushed them.