Thomas Graf (born 28 September 1944) is a biologist at the Centre for Genomic Regulation (CRG) in Barcelona, Spain.

[3] In the late 70s Graf co-discovered several cell-derived oncogenes acquired by avian retroviruses, designated Mac (later changed into Myc), Erb and Myb.

[4] He found that several naturally occurring virus strains have acquired various pairwise combinations of oncogenes and that these cooperate to cause acute leukemia,[5] an early example for the multigenic origin of cancers.

[6] In his more recent research he showed that different types of specialized blood cells can be induced to convert into each other by forced transcription factor expression.

[10] Finally, he found that forced C/EBPa expression in malignant lymphocyte precursors leads to the formation of macrophages and loss of tumorigenicity,[11] suggesting transdifferentiation as an alternative avenue for therapeutic interventions.