Beast was created in 1984 by Dan Baker, Alan Brown, Mark Hamilton and Derrick Shadel, but it's Dan Baker who is listed as the main author. Unfortunately this is not an uncommon name, and it is therefore nearly impossible to find out anything about him. In the late 90s there is a Dan Baker at Electronic Arts, but I very much doubt that they are the same person.
One remarkable thing about Beast (well, remarkable in my eyes at least) is that it uses two characters as a unit, resulting in near-square tiles and sprites. Tetris and many Tetris clones did the same, but otherwise I have never seen it.
The gameplay? The red H-shaped critters are beasts. Everything that is yellow is solid wall. Everything that is green is blocks you can push. The beasts are after you. You have to try to crush them between two blocks, or shut them into a confined space where they will turn insane and explode. Whenever a beast gets you, you lose one life. Luckily you can run faster.
At first I felt rather lost. A good strategy, I soon found out, is to lock yourself in in the beginning: build yourself an impenetrable fortress, and then slowly expand it. The beasts are dumb, they'll try to get at you even though they can't, and put themselves in positions where you can crush them with ease.
Beast has three speed settings, for PC, PCjr, and AT. If you guess that it won't run well on anything faster, you guess right. I played it on my IBM PS/2 50.
There is a faithful, but unfinished Unix port by Kevin Turner from 1999 under the title Beasts, but the homepage is gone, I have no idea where it can be found now. SqueezePlay is a fairly faithful remake for Windows, while Rodent's Revenge has similar, but not identical gameplay. Monster Masher is a game for the Gnome desktop environment based on the same premises, but with additional features like monsters laying eggs, or monsters that must be crushed against walls.