Is brands names imitating illegal?

I came across a lot of products using some weird names that almost look the the same as popular brands names, for example "Acliclas" as a rip-off of "Adidas" and "Huowei" as a rip-off of "Huawei", do you think that this is an illegal thing to do ? does the original companies have the right to take down those rip-off brands and sue them ?