Brendan Schaub -- former UFC star and comedian -- saved 3 children from a terrifying car wreck last week ... after their father allegedly drove the wrong way on the highway, killing the kid's mom in a fatal collision.
38-year-old Schaub was driving to a restaurant with his girlfriend on August 12 around 7PM ... when he saw an 18-wheeler and a mangled 2003 Lincoln were involved in a serious accident.
Schaub says he saw a child sitting on top of the vehicle, screaming for assistance ... so he pulled over and immediately sprang into action, rushing to the car to help.