strong silent type - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
A man of action who is reserved and masks his feelings. For example, Paula always preferred the strong silent type to more extroverted men. Almost never used for a woman, this expression may be obsolescent. [c. 1900]