You didn't say which meaning of the word you wanted to use. If you mean behind as in lagging and not with the rest of the group, you could say "He was behind us." You might also hear "She was behind the times" to mean that she was a little old fashioned. If you mean behind as a slang for buttocks, you can say "Mom smacked me on my behind for talking back to her."
He was supposed to be there at seven, but he was running behind. In the hurry to evacuate, his laptop was left behind.
Alert, there's a creeper behind you!
An amorphous figure came out from behind the curtain.
She pivoted her body around to talk to the person behind her.
Then a hail of gunfire splattered the wall behind him.
They tried to manipulate the politicians behind the scene.
Poverty is behind most crime in inner cities.
My Friend oversaw a person behind him.
The surly man behind the desk was most unhelpful
The forerunners, or ancestors, left behind relics of their greatness.
I walked down the corridor, and heard footsteps behind me?
behind