I’m a firm believer in self-promotion or blowing your own horn if you will. There is value in sharing your contributions to a project, your skills in helping to establish your worth to the organization. However, if the individual is blowing their contribution out of proportion at the expense of the other team members gaining recognition, then they are a braggart.
Having never met the individual in question it would be difficult to assess their actions. I work in mental health/psychiatry. There is an adage I use regularly throughout my career in situations like this. “All behaviour has meaning." The challenge of course is in determining what their behaviour is hoping to achieve.
It sounds to me there are several problems going on with this individual. Firstly, they either have no problem lying or they don’t realize they are lying when they take credit for other's work.
Secondly, they do not appear to be a team player. It seems to be all about them. I would suspect that throughout their life they’ve learned to suck up to managers, supervisors etc. as a way to garner recognition. If nobody challenges this behaviour it will likely continue as it has proved to be successful for them in the past.
Thirdly, assuming the rest of the team is aware of this behaviour, I would have to ask what are they going to do about it?
Now addressing the first part of the question what can you do about it if it is affecting you personally…
The best way to handle any interpersonal conflict is to do so in an assertive manner.
I would invite the individual for a discussion of how you’re feeling about this situation. This isn’t the time for pointing a finger and chastising the individual.
Assertive communication as an example goes like this “I feel devalued/cheated/disrespected/taken advantage of when you take credit for my efforts.”
Two key points in that simple sentence: “I". By saying I you are taking responsibility for your own feelings. When you say "you" in addressing the individual you are making it clear that you are referring to them and holding them accountable.
A common and ineffective statement that many people make is “you make me feel this way when you do this." When you’re using the word “you" in this manner it is easy the other individual to become defensive and not accept what you have to say.
The next step would be to advise the individual that their behaviour of taking credit for work you have created has to stop immediately. And if it doesn’t, here are the steps you are going to take. This may include having a meeting with your manager, having a team meeting and/or raising the issue at a staff meeting.
Good luck with this. Unless this behaviour is challenged it will continue.