That is Grimace.
He is a pug.
He is an "old pug."
He is a "love bug" pug.
He is a devoted pug (obsessively devoted - to the point of scary at times -apparently typical of the breed.)
He is a "special needs" pug (needs Pooch Pants, sometimes call Camp Trousers, or doggie diapers, to prevent ... well ... you know. (Also typical of the breed, I am afraid.)
But a dearer, sweeter, more underwhelming pooch you will never find.