Near Rhymes:
* Bennett
* Grennett
* Rennet (a type of cheese)
* Tennet (a brand of beer)
Eye Rhymes:
* Beth
* Seth
* Death
Slant Rhymes:
* Kenneth and Janet (both have the "et" sound, but the vowel sounds are different)
* Kenneth and Clement (both have similar vowel sounds, but different endings)
Ultimately, the best rhyme for "Kenneth" will depend on the context and the effect you're trying to achieve.