Red Line service was halted when a shirtless guy jumped on the inbound Red Line tracks at Andrew and went for a jog down the tracks  underneath South Boston. He was never found.
A woman failed to stop walking at Broadway station until she fell onto the tracks :
Ten days later, another woman walked off the platform  at Andrew:
Somebody else also fell on the tracks at Mass. Ave. on the Orange Line .
Guy walking on the Orange Line tracks outside Malden Center got hit by a train , but lived.
An out-of-towner fell on the tracks  at Kendall.
Somebody fell on the Orange Line tracks  at Wellington.
A man who "suddenly entered" the Blue Line tracks at Maverick was hit by a train and died .
Commuter-rail trains out of Back Bay were delayed by napper .
A woman fell on Orange Line tracks at State Street  - managed to wedge herself into one of those cutouts just as a train came into the station.
OK, not on the tracks, but that woman tried to ride her motorized wheelchair up the escalator  at Broadway. It did not end well. A man who rode his bike up the escalator at Forest Hills spilled his coffee .
An out-of-town man fell on Red Line tracks  at Central Square, was pulled to safety:
A man slipped under a Green Line train  at Haymarket; bystanders alerted the driver to not go:
- Boston 
- The T