A Matplotlib developer is responsible for creating visual representations of data using the Matplotlib library in Python. They generate graphs, charts, histograms, scatter plots, and other statistical graphics to effectively communicate complex data trends and patterns. Their tasks may include data cleaning, analysis, and visualization. They also ensure the accuracy and reliability of the data presented. Additionally, they may customize the appearance of the graphics to make them more comprehensible and visually appealing. They often collaborate with data scientists, statisticians, and other stakeholders to understand their data visualization needs and provide appropriate solutions.