Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| No. by series | No. by season | Title | Directed by | Written by | Original air date | Production number | U.S. viewers (in millions) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 59.0 | 1.0 | "Rise" | Rob Bowman | Andrew W. Marlowe | September19,2011 | 401.0 | 13.28 |
| 60.0 | 2.0 | "Heroes & Villains" | Jeff Bleckner | David Amann | September26,2011 | 402.0 | 11.67 |
| 61.0 | 3.0 | "Head Case" | Holly Dale | David Grae | October3,2011 | 403.0 | 11.18 |
| 62.0 | 4.0 | "Kick the Ballistics" | Rob Bowman | Moira Kirland | October10,2011 | 404.0 | 10.23 |
| 63.0 | 5.0 | "Eye of the Beholder" | John Terlesky | Shalisha Francis | October17,2011 | 405.0 | 11.23 |
| 64.0 | 6.0 | "Demons" | Bill Roe | Rob Hanning | October24,2011 | 406.0 | 10.81 |
| 65.0 | 7.0 | "Cops & Robbers" | Bryan Spicer | Terence Paul Winter | October31,2011 | 407.0 | 12.58 |
| 66.0 | 8.0 | "Heartbreak Hotel" | Bill Roe | Elizabeth Davis | November7,2011 | 408.0 | 11.07 |
| 67.0 | 9.0 | "Kill Shot" | David M. Barrett | Alexi Hawley | November21,2011 | 409.0 | 10.85 |
| 68.0 | 10.0 | "Cuffed" | John Terlesky | Terri Miller & Andrew W. Marlowe | December5,2011 | 410.0 | 8.12 |
| 69.0 | 11.0 | "Till Death Do Us Part" | Jeff Bleckner | David Grae | January9,2012 | 411.0 | 9.76 |
| 70.0 | 12.0 | "Dial M for Mayor" | Kate Woods | Christine Boylan | January16,2012 | 412.0 | 9.41 |
| 71.0 | 13.0 | "An Embarrassment of Bitches" | Tom Wright | Rob Hanning | January23,2012 | 413.0 | 10.05 |
| 72.0 | 14.0 | "The Blue Butterfly" | Chuck Bowman | Terence Paul Winter | February6,2012 | 414.0 | 8.70 |
| 73.0 | 15.0 | "Pandora" | Bryan Spicer | David Amann | February13,2012 | 415.0 | 8.86 |
| 74.0 | 16.0 | "Linchpin" | Rob Bowman | Andrew W. Marlowe | February20,2012 | 416.0 | 9.73 |
| 75.0 | 17.0 | "Once Upon a Crime" | Jeff Bleckner | Kate Sargeant | February27,2012 | 417.0 | 9.10 |
| 76.0 | 18.0 | "A Dance with Death" | Kevin Hooks | Moira Kirland | March19,2012 | 418.0 | 11.52 |
| 77.0 | 19.0 | "47 Seconds" | Paul Holahan | Shalisha Francis | March26,2012 | 419.0 | 11.87 |
| 78.0 | 20.0 | "The Limey" | Bill Roe | Elizabeth Davis | April2,2012 | 420.0 | 11.69 |
| 79.0 | 21.0 | "Headhunters" | John Terlesky | Alexi Hawley | April16,2012 | 421.0 | 11.23 |
| 80.0 | 22.0 | "Undead Again" | Bill Roe | Christine Boylan | April30,2012 | 422.0 | 11.08 |
Question:
Who directed episode 21?
Answer:
John Terlesky