Beef bouillon is a concentrated beef broth used in some savory drinks. It is also called beef stock.
Quality beef bouillon is usually made from scratch. This involves cooking down beef scraps and bones into a rich broth. If you are using bones, paint them with tomato paste and roast them for a short time first. You really have to like a Bloody Bull or other drinks that have beef bouillon in them if you make the beef bouillon from scratch. More power to you if you go this route.
But if you're after premade bouillon, there are viable choices out there. Stay away from the canned stuff--too much salt and not enough flavor. Also, the Knorr and Tones cubes are still too salty, though they are better than the canned stuff.
If you don't want go the scratch route but you still want to blow your guests away, there is a product that is head and shoulders above any beef bouillon I have ever tried. It is More Than Gourmet Glace de Viande Gold. More Than Gourmet uses classic French techniques to create this reduced brown stock. It tastes amazing with rich beef flavor without too much salt. In fact I like it better than my homemade stock.
I get the one pound tub because it keeps for months in the refrigerator and I use it to make all kinds of sauces along with Bloody Bulls. But it comes smaller packages if you wish.