A Buddha (distinct from Gautama Buddha) popular in the Pure Land school of Mahayana Buddhism.
When Amitabha learned the Four Noble Truths, he vowed that after he becomes Buddha he would create a Pure Land. He also vowed that anyone who, at the time of death, invokes Amitabha's name will be reborn into his Pure Land, and live a long life free of suffering.
A person reborn in Amitabha's Pure Land can study the dharma, and get all the reaction to their prior karma slowly, hence without suffering, and eventually realize awakening.
Many Mahayana Buddhists practice Zen in the morning, Pure Land in the evening (or the other way round, I do not remember exactly, sorry).
Completely subjective personal note: I am not too attracted to the idea of invoking Amitabha's name at the time of my death. It could be because I am an ex-Christian, and Amitabha is too much of a Christ-like personal savior to me (I know this is a completely biased opinion, and traditional Asian Buddhists probably do not view it that way).
More importantly, it is a trade-off. Life on this plane is filled with suffering, all right, but it leads to awakening pretty fast, is a nice challenge, and generally interesting. It is no coincidence I have originally chosen to live on this human plane. I would probably be totally bored in Amitabha's Pure Land. And as my Zen teacher pointed out, this plane, too, is a Pure Land, namely Sakyamuni's Pure Land, which he created for the same purpose as Amitabha did his, but using different means of coming to awakening.
The trade-off I started talking about is: Either get it done fast but suffer in the process, or make yourself comfortable but wait and wait and wait...
Anyway, this is just my own view point, you should choose whatever appeals to you. That's the beauty of Buddhism: There is more than one way.