You can use the following address to send fan mail to Jim Parsons.
9255 W Sunset Blvd
West Hollywood, CA 90069
(this address may not be correct, but it should be)
How it Works:
If you live in USA and want a signed photo back you need to send a properly stamped and self addressed envelope with your request letter and a photo for him to sign (he may have his own but better be safe than sorry).
If you do not live in USA, make sure to add an International Reply Coupon. The International Reply Coupon (IRC) will be to purchase american stamps. You can only get them at your post office. Put the IRC inside the envelope, not on it, your postal worker will know what to do.