Cement production is among the biggest sources of carbon emissions worldwide, and the construction sector as a whole puts enormous pressure on natural resources. This has pushed researchers toward more sustainable cement-based materials, exploring natural and waste fibres as a form of reinforcement. Fibre-reinforced mortars have long been valued for better fracture toughness and crack resistance, but achieving this has meant depending heavily on inorganic or synthetic fibres. That dependency is now the problem researchers are trying to solve, with bio-based alternatives emerging as a promising direction. Among all natural fibres, sheep wool stands out as a uniquely promising material, it is renewable, widely available, and naturally produced.