2x01 -In My Time Of Dying

Elroy McGillicutty
This is the name on the card that John gives to Sam for the insurance.

2x02 -Everybody Loves A Clown

No aliases used

2x03 -Bloodlust

Reporters for Weekly World News
Trying to find out more information about the beheadings and the cattle mutilations, the boys pose as reporters for Weekly World News, a newspaper famous for its coverage of supernatural and unexplained events.
Doctors / Interns
Now needing to look at the body, they don white lab coats and pose as interns at the morgue.

2x04 -Children Shouldn't Play with Dead Things

Friends of Angela Mason
When they want to find out more about Angela, they go and visit her dad, pretending to be friends of hers.
Alan Stanwick
Dean breaks into Angela's apartment, only to find her flatmate still there. He says he's Angela's cousin and gives this fake name as an alias. Alan Stanwyck (Tim Matheson) is the one of the main characters in "Fletch" (1985).

Grief Counselors
When they want to talk to Neil, they pretend to be grief counselors from the local college.

2x05 - Simon Said

Lawyers
They go looking for Andy Gallagher, saying that they are representing his Great Aunt Lena who has left him something in her will.

2x06 -No Exit

Apartment Hunters
Not actually the boys idea, but Jo introduced Dean as her boyfriend and Sam as his buddy when they were invesigating the apartment.

2x07 - The Usual Suspects

Insurance Investigators
When they go to visit Karen Giles, they tell her that they are from an insurance company investigating her husband's death.

2x08 -Crossroad Blues

Reporters
Investigating Sean Boyden's death, the boys pose as reporters from Architectural Digest. Animal Control Officers
When they are looking for Sylvia Pearlman, they tell her maid that they are from Animal Control.

2x09 -Croatoan

Billy Gibbons and Frank Beard - US Marshals
When they meet Mark for the first time, they introduce themselves as US Marshals and then continue the pretense throughout their time in the town. The real Billy and Frank are members of the band ZZ Top.

2x10 -Hunted

Scott's Schoolmate
When Sam starts looking into the other special children, he talks to Scott Carey's dad, telling him that he was a High School friend of Scotts.

2x11 -Playthings

Mr Mahagov - Antiquer
When they check into the hotel using Dean's alias, Susan assumes that they are antiquers.

2x12 - Nightshifter

FBI Agents
Resorting back to a standrd chat-up line, Dean pretends to be an FBI Agent, athough this time Sam pretends to be one too.
Securiserve Guard Service
They pretend to be workers for Securiserve to gain access to the security cameras in the bank.