Not much biographical information on Henry was on the Internet when I drafted this post, so make do with this brief Wikipedia entry. More can be found in Roger Billcliffe's book about the Glasgow Boys.
I find Henry and most other "Boys" interesting because their works show us that there was a lot more going on in the art world of the 1880s than the Impressionism and post-impressionism in France that histories of art still focus on.
Two fairly early landscapes.
One of Henry's best-known paintings.
The brushwork, color usage and clutter suggests the influence of E.A. Hornell, a fellow Glasgow Boy. They spent a year and a half in Japan around 1894 and jointly painted "The Druids" (see below).
This somewhat distorted and decorative painting is considered significant by art historians and critics because of its use of modernist elements.
Another painting with more modernist influence than usual for Henry. By the early 1900s he reverted to a more traditional painting style, even eliminating Glasgow Boys elements.
Henry and Hornell made paintings featuring young girls. Henry did this for a comparatively short time, but the latter part of Hornell's career was largely based on such subject matter.
A work jointly painted with Hornell. This painting has always fascinated me, so I visit it whenever I'm in Glasgow.