Mary Johnson Ambler (March 24, 1805 – August 18, 1868) was an American humanitarian and fuller who helped organize the rescue of survivors of the Great Train Wreck of 1856 in Pennsylvania.

The widowed Mary and her married son, Lewis, continued to run the mill until she died on August 18, 1868, and was interred at the Gwynedd Friends Meeting cemetery.

She started a Sunday school, permitted neighbors to draw water freely from her well, and gained local recognition for charitable endeavors.

[3] At 6:15 am on July 17, 1856, two passenger trains running on the same track collided head-on between the Fort Washington and Camp Hill stations.

[1] When Ambler learned about the wreck, she gathered bandages and other medical supplies and walked several miles to the scene of the disaster, where she calmly and methodically ministered to the injured and directed rescue efforts.