It's not relevant today but a well-known virologist, Peter Duesberg, was an HIV-causes-AIDS denialist (before that he was very well known for real accomplishments in virology). However, he never showed any evidence to support his case and there was extensive evidence against it. If you want to be a denier, the reality is that you have to show a lot of compelling evidence both supporting your position, and against the mainstream position.

Modern denialism tends to be more centered around climate change- whether it is occurring, and what the impacts will be in the near and long term, and how to respond. Many physics people (who worked on high energy particle physics, etc) have looked at the claims from the various climate change promoters and found the source evidence to be less than convincing. If they articulate this, they are often described as denialists. Here's an example: https://en.wikipedia.org/wiki/William_Happer