Is there such thing as an alligator and a monkey mixed together?

In the natural world, no, there is no such crossbreed. Among legendary creatures, no doubt someone has invented or claimed to have seen just such an amalgamation, however, no popular information seems available at the current moment.

鳄鱼和猴子是两种完全不同的生物，分属于爬行动物和灵长类动物，它们之间没有可以混合的生物学基础。所以，鳄鱼和猴子混合在一起这种情况是不存在的。如果你是在问关于某种神话生物或者混合动物形象，那这通常只存在于虚构故事或卡通、电影等娱乐作品中。