How to read the band →
Solid line = floor (spellings that unambiguously belong to the group). Shaded band up to the dashed edge = ceiling (the most it could reach if every ambiguous spelling counted here).
Killian
Killian has been climbing in recent years. All-time it's been given to 24,674 U.S. babies, the 379th most common name by sound today, peaking at 2,323 in 2023, with 1,828 in 2025.
By sound, Killian also includes the spellings Cillian, Kylian.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).