Serial killers are larger and show stronger and faster responses. (A) Scheme showing conjugation periods (red) and target cell killing events (yellow lines) for the 10 detected NK serial killers. (B) Percentage of fast and slow kills and times (C-E) measured for serial killers (serial), all cytolytic interactions (all kills), and all cytolytic interactions except those performed by serial killers (other). (C) Conjugation time. (D) Time to lytic hit. (E) Time to target cell death. (F) Mean cell area for serial killers (serial) and all NK cells that killed at least one target cell during the experiment (kills).