I work with a controlling co-worker. Dealing with him though is not so difficult as long as I am not accomplishing too much. Once he finds out my new tasks at work he tries to take them over and try to accomplish them himself even saying it to the boss that he should do the job and how it is not fit for me. Also, he invites himself on other activities that no one invited him on so that he looks good. I think these last two things are giving me the most problems and I do fear that I may lose a chance to accomplish the most possible from my position. I think I need some advice and to let me know the best possible way to deal with this situation.

What you are dealing with is a 'workplace bully'. It is a relatively new phenomenon that over the past few years has resulted in awareness training. That has come about because the stress caused by workplace bullies costs money in sick days and benefits. I have also heard that companies not addressing issues caused by these bullies, are subject to legal troubles too.

I recently worked with a co-worker like you described, only female. She used information on me (personal), to spread rumours, and cause me a lot of grief. I reported her, and the company had followed the policy to deal with this type of abusive behaviour.

She was given a warning, told to stop, and failure to do so would result in instant dismissal.

Ignoring people like this isn't the answer. They are manipulative, self-centered, and driven to use anybody in their way to get ahead.

I think that if you confront him, or speak to the supervisor, you may or may not curb his behaviour. But, if he's on a path to make your life (and probably others) miserable, it might be a good idea to recognize the type of bully he is, and research how to deal with him.

http://www.safety-council.org/info/OSH/bully.html

So you tell him to butt out, you go to your boss and tell them he is hurting your work and ask for them to keep him out of your work.

Go to the boss

It sounds like this person doesn't want you to look like you know what you're doing; they probably feel threatened by you. I can relate, my supervisor where I am currently working acts similar to that, and is definitely a bully. (He alternates between what you described, and being overcritical, controlling, and expecting too much). I have worked there for almost 2 years, and I wish I drew the line early on and stood up for myself. The longer you wait to defend yourself and set healthy boundaries, the harder it is to do so. Since this person is your coworker and not your superior, right? It should be a little easier to set boundaries. Just tell him you are confident you can tackle those tasks.

I guess maybe he wants to get more credit so he can get promoted faster. However, I've seen people get credit and recognition from others' work. I guess that's a worse case than this, at least he's doing job for you :) agree?