[Nexus 6  General] rishabhgangwar:
All ROMs (Stock & Custom)

Stock ROM:

[Official] Factory Images for Nexus Devices along with flashing instructions can be found here:

https://developers.google.com/android/nexus/images

[XDA] Another guide to flash factory files:

[26-11-2014] [TUTORIAL][GUIDE][HOW TO] Flash Factory Images || Unroot || Relock bootloader By Mr hOaX

Custom ROMs:

Android Development

[19-01-2015] (ROM)(5.0.2)(VALIDUS-LP-v7.0) By Doddzilla

[18-01-2015] [ROM][Official][5.0.2][Shamu] Dirty Unicorns v9.0 By spaceman860

[13-01-2015] [ROM] [5.0.2] [LRX22G] [UNOFFICIAL] Beanstalk [LOLLIPOP] [01/12/15] By PWn3R

[12-01-2015] [ROM][5.0.2][LRX22G] Chroma – 01/11/2015 By zephiK

[11-01-2015] [ROM] Candy5 Official RC | 5.0.2 | 1.10.15 By mar5hal

[10-01-2015] [ROM][1/9/15] - Stock DEODEXED 5.0.1 LRX22C | Debloated | Unencrypted By jermaine151

[10-01-2015] [ROM][LRX22C][5.0.1][15 Jan 2015]xTraSmooth 1.2 Odex xTreMe Battery You Will Love It By daniel84cs

[07-01-2015] ROM[official][shamu][5.0.2][jan7]**crDroid** By firebird11

[03-01-2015] [ROM][1/17/15] - CleanROM 1.2.5 -★| 5.0.1 | Cleaner! | Smoother! | Super Stable! |★- By scrosler

[29-12-2014] [ROM][UNOFFICIAL][Nightly] AICP By RIPng

[28-12-2014] [ROM] Terminus [Android 5.0.2_r1 LRX22G][shamu] By lichti1901

[25-12-2014] [ROM][Official]BrokenOS By RIPng

[23-12-2014] [ROM][Unofficial] Bliss Pop 1.3 [12/23/2014] By asianflavor

[22-12-2014] [*Updated 23-12-2014*] [ROM] [5.0.2] [LRX22G] [UNOFFICIAL] Vanir [LOLLIPOP] [12/22] By PWn3R

[22-12-2014] [ROM][12/21/14] - Stock Rooted 5.0.1 LRX22 -★| Stock | Root | Unecrypted |★- By scrosler

[20-12-2014] [*Updated 24-12-2014*] ★☆★[ROM] N6 Nocturnal Limited Edition v2.0.3|LRX22C|Dec 20th 2014|★☆★ By XsMagical

[15-12-2014] ★ ☆ [ROM][KERNEL][5.0.1][OFFICIAL]LiquidSmooth v4.0 | Nexus 6 (shamu) By CPA Poke

[15-12-2014] [ROM][12/19] Pure AOSP ROM -★| 5.0.2_r1 | LRX22G | Build #3 By scrosler

[14-12-2014] [ROM][Official][5.0.2 LRX22G] Resurrection Remix By asianflavor

[10-12-2014] [ROM][UNOFFICIAL][shamu][5.0.1] Omni Rom [ALPHA] By ##W4TCH0UT##

[08-12-2014] [*Updated 28-12-2014*] [ROM][DEC 28][Team Nocturnal] SinLessROM v2.0.2 | Android 5.0.1 By mrjaydee82

[07-12-2014] [*Updated 15-01-2015*] [ROM][5.0.2][LRX22G] Lollipop Dream [Linaro][Build 11][20150116] By upndwn4par

[07-12-2014] [ROM] Elix-R | V2.0.1 | 5.0 + 5.0.1 Hybrid | 12/07 | Fast | Simple | Elegant | By Zyxxeil

[28-11-2014] [ROM] [LRX22C] Minimus for Nexus 6 By jarjar124

[27-11-2014] [*Updated 20-12-2014*] [ROM][5.0.2][Shamu][DEC 20] Euphoria-OS 1.0 By dsmitty166

[25-11-2014] [*Updated 21-12-2014*] [ROM][5.0.2][LRX22G][Dec 21] || Pure Shamu b3.4 By error311

[25-11-2014] [ROM] [NOV 25][Team Nocturnal] NOSP By mrjaydee82

[23-11-2014] [ROM] (AOSP)Lollipop AOSP By papi92

Original Android Development

[15-12-2014] ★ ☆ [ROM][KERNEL][5.0.1][OFFICIAL]LiquidSmooth v4.0 | Nexus 6 (shamu) By CPA Poke [Moved to Android Development]

[10-12-2014] [ROM][UNOFFICIAL][shamu][5.0.1]Omni Rom By ##W4TCH0UT## [Moved to Android Development]

[03-12-2014] [ROM] RASTAPOP [Android 5.0.1_r1 LRX22C] [PRODUCT_DEVICE := shamu] By rascarlo

[03-12-2014] [ROM-AOSP] Official SlimLP By Jubakuba

CyanogenMod Based ROMs

[13-01-2015] [ROM][OFFICIAL][5.0.2]Team UB Rom for NEXUS 6 ( shamu ) ![13/1/15] By BigBossTech

[05-01-2015] [ROM][5.0.2] SaberMod CyanogenMod+ By xanaxdroid

[31-12-2014] [DAILY][UNOFFICIAL] Stock CM12 builds [31.12.2014] By inffy

[10-12-2014] [*Updated 21-12-2014*] UnOfficial CM-12.0 Shamu By skiwong20