Hisham ibn Al Hakam is one of the most well known shia rafidhi figures. They call him one of the main companions of Jafar Saddiq & a top shia scholar of his time. Funny enough, this same hisham is said to have authored books against other so called top 'shia companions' of Jafar Saddiq, even labelling them 'shaytan' (search on this forum for this).
It is well known hisham believed in tajsim attributing ugly things to the almighty & likening him to the creation. Both sunni & shia sources document this.
Now here's an interesting scenario, according to shia texts, hisham was held responsible for the death of the '7th Imam' Musa al khadim.
Musa had ordered Hisham to stop debating during the caliphate of al-mahdi due to the danger posed on the Imam's life. Hisham refused and said "persons like me cannot be restrained from debate". Hisham was consequently held responsible by some Imamis for the Imam's death.
The '9th Imam' Al Jawad is reported to have instructed a disciple not to pray behind followers of Hisham.
[Source: al kashshi's Rijaal]
One prominent shia scholar who wrote a book about the various shia sects was Sa'd ibn Abd Allah Ashari Al Qummi who lived during the 3rd Islamic century & lived during the time of the '11th Imam' & the minor occultation of the '12 Imam'. He composed a treatise called "The Book of the Blemishes of Hisham & Yunus (another shia figure)".
[source: Sa'd ibn Abd Allah Al Ashari Al Qummi's kitab al maqalat wa al firaq]
Th first to start defending Hisham in order to do a clean up on his dodgy character was al mufid who died in 413 AH. Its clear when one reads about the likes of Hisham ibn Al Hakam, Zurarah, shaytan al taq, Jabir Al Jufi, etc, one will see how later shia scholars had to chop & change their image to suit the later shia scholars claims to of legitimacy of being the representatives of the hidden Imam.