Precisely identifying entities in web documents is essential for document indexing, web search and data integration. Entity disambiguation is the challenge of determining the correct entity out of various candidate entities. Our novel method utilizes background knowledge in the form of a populated ontology. Additionally, it does not rely on the existence of any structure in a document or the appearance of data items that can provide strong evidence, such as email addresses, for disambiguating authors. Originality of our method is demonstrated in the way it uses different relationships in a document as well as in the ontology to provide clues in determining the correct entity. We dem-onstrate the applicability of our method by disambiguating authors in a collec-tion of DBWorld posts using a large scale, real-world ontology extracted from DBLP. The precision and recall measurements provide encouraging results.