Jeremiah, it's interesting that you would ask this question. In the old testiment, otherwise known as the Hebrew Scriptures because of its being written primarily in that language as well as Aramaic, there are serveral references made about Jesus. One of them is found in the book of Proverbs chapter 8. In reading the entire chapter for proper context we see the creation of things pertaining to physical creation being related. Then, starting in verse 30 note what the Bible says:
"vs 30 then I came to be beside him as a master worker, and I came to be the one he was specially fond of day by day, I being glad before him all the time, vs 31 being glad at the productive land of his earth, and the things I was fond of were with the sons of men."
Who is this I, that came to be beside God as a master worker?
Well, The expression: "came to be beside him as a master worker", indicates that the person speaking has a very special relationship with the creator. Does this mean that the person speaking was a human? No it does not. This is indicated by looking up a few verses into the context of the reading. At verses 25 and 26, the person talking makes it clear that he was in existance before the earth had been created. So that rules out the possibility of this being a human speaking. And when you do further research, you will find that the Bible indicates that the expression of: "then I came to be beside him as a master worker," is explained in other portions of the Bible. One of which is Luke 22:69 where Jesus is seen sitting at the right hand of God or "beside him." No where in the Bible is anyone other then Jesus ever described as having such a close and favored position with God. The Scriptures only assign this honor to Jesus. So, to answer your question: "Was Jesus ever mentioned in the Old Testament?" The answer is simply, yes.
I hope this helps. Feel free to contact me if you have further questions.