A thought was creeping into his mind that had no place in the organization there.

A strange and yet persuasive thought crept into his mind.

A thought had crept into my head, going back to that first day.

But no matter what everyone says, dark thoughts creep in.

The thought creeps into my head, as it's done a few times before.

From out of nowhere, another thought crept up and bit him.

As if it ever would be, the thought crept back into his mind.

The thoughts he had been trying to hold at bay for the last week crept in.

It's hard not to let those thoughts creep into your mind.

A thought crept through the back reaches of his mind, one he did not like at all.