A clinical trial participant , someone that has consented to taking part to received an clinical trial treatment.
You can also get involved in Patient and Public Involvement (PPI) group in clinical research. PPI aims to ensure that research is relevant, meaningful, and responsive to the needs, preferences, and priorities of the people it seeks to benefit. This is very different to being a clinical trial participant, it often involves being part of group that supports researchers develop research ideas or patient protocols / information for clinical trials. If you are interested in getting involved in PPI contact.