I am quite certain that there are more deadly mushrooms than just the one you mentioned - if only for the other members of the Amanita Genus, many of which are very poisonous and some plain kill you.
E.g. Amanita Vitrosa, with the uncommonly poetic name destroying angel (German: Weisser Knollenblätterpilz), is just as deadly as the one you mentioned. What makes it potentially even more dangerous (or at least I was told so by several people who taught me mushroom foraging as a kid) is that it has some similarities to the Agaricus (German: Champignon), some of which are commonly collected for eating. Apparently it happens that people mix them up and get themselves killed this way.
Bottom line: Best don't touch anything from the Amanita Genus. From Wikipedia:
Although some species of Amanita are edible, many fungi experts advise against eating a member of Amanita unless the species is known with absolute certainty. Because so many species within this genus are so deadly toxic, if a specimen is identified incorrectly, consumption may cause extreme sickness and possibly death.
2nd Bottom line: know your mushrooms. Stick to the ones you know well and are clearly distinguishable from poisonous members of the Fungi kingdom.
If ever in doubt, don't eat them - or get the mushrooms tested first: I don't know about other places, but in Switzerland in mushroom season there are designated mushroom control offices where people can bring their finds and have them looked at by a fungi expert. (See VAPKO, page in German/French/Italian)