Current European, and particularly Mediterranean, agricultural production systems heavily depend on protein imports to cover the nutritional needs of farmed animals and fish. To increase their resilience, the EU is in search of efficient, sustainable, and locally produced alternative proteins. Insects and algae have recently gained much attention due to their ability to bioconvert agro-industrial side-streams into valuable resources. Legumes are known for their high protein content; however, certain species, such as lupins and fava beans, have been overlooked and underused as food and feed. Additionally, microbial fermentation can be used in parallel with insects, algae, and legumes, to efficiently transform them into food and feed. This contribution describes the challenges and chances associated with the utilization of these alternative protein sources for food and feed applications.