|Family||unnamed wife, Martha Kent (daughter), Jonathan Kent (son-in-law), Clark Kent (adopted grandson)|
|Played By||George Coe|
|Last Seen||Redux, 2002|
He expected Martha to become a lawyer and eventually take over his practice. When Jonathan Kent asked him for Martha's hand in marriage, William objected, saying his daughter deserved better than some farmer. Jonathan hit William, and the two didn't speak again for years.
William Clark tried to later reconcile with Martha and Jonathan after they adopted Clark. However, Martha decided that their long-standing history of disagreement prevented them from trusting William with Clark's secret, and Clark was too young to control or conceal his powers, so Martha and William never reconciled. Clark tried to contact his grandfather a few times, but received no answer.
Martha had no contact with her father for 12 years until she went to him for financial help to keep the farm from going under. He came to Smallville and Clark finally met his adoptive grandfather. Clark tried in earnest to get his family to set aside their differences. William provided the financial assistance, but to Clark's disappointment, Jonathan and William did not really reconcile. (Redux)
Later that year, when Jonathan was falsely accused of shooting Lionel Luthor, Martha planned to ask her father to defend him. However, Jonathan rejected the idea, telling his wife that William had never believed in him before and he did not think that an attempted murder charge would do anything to change his mind. (Suspect)
- Season Two: Redux, Suspect (Mentioned only)
- Season Four: Crusade (Mentioned only)
- Season Ten: Beacon (Mentioned only)
- Clark Kent was named by Martha after her maiden name. (Lineage)
- As of 2011, William still appears to be estranged from his daughter and her family. He didn't attend Clark's high school graduation in 2005 (Commencement), Jonathan's funeral in 2006 (Reckoning) or Clark's wedding to Lois Lane in 2011. (Finale, Part 1)
- In the comics, on Earth-One, Martha's father was named Hudson Clark.
- He was similar to General Sam Lane in Ambush.