- Judson (continued)
- Juede
- Julian
- Jungferman
- Jungman
- Justi
- Justus
- Jzabel
- Kaba
- Kacher
- Kahler
- Kahn
- Kaine
- Kaiser
- Kalee
- Kalinowski
- Kalvelage
- Kammeraad
- Kane
- Kaneen
- Kannady
- Kanous
- Kaple
- Karam
- Karich
- Karl
- Karlson
- Karner
- Karns
- Karst
- Karstens
- Karstensen
- Kartsounis
- Kaske
- Katial
- Kau
- Kauffman
- Kaufman
- Kaven
- Kaviani
- Kay
- Kayanagi
- Kazanjian
- Kearl
- Kearney
- Kearns
- Keast
- Keating
- Keaveney
- Kecke
- Keefe
- Keele
- Keeler
- Keen
- Keenan
- Keene
- Keeney
- Keesecker
- Keet
- Kehm
- Kehoe
- Kehrer
- Keigher
- Keillor
- Keirnan
- Keith
- Kelemen
- Kelleher
- Keller
- Kelley
- Kelling
- Kellog
- Kellogg
- Kellow
- Kellum
- Kelly
- Kelsea
- Kelsey
- Kelton
- Kemble
- Kemp
- Kempe
- Kempton
- Kendal
- Kendall
- Kendrick
- Kendricks
- Kennedy
- Kenney